3D printing is a technology for additive manufaturing. In contrast to eg. CNC milling, there is no material taken away to produce a part but material is added until a part is built.[br]It can be compared a bit to the difference between a sculpture where a person is carved out of a rock like Michelangelos David in contrast to a snowman where snow is collected in balls until a hat and a nose can be attached.[br]Material is usually added in layers, like a cake often consists of layers that are connected by some cream. For 3D printing, the layers can be connected in different ways, regarding on the technology.[br]

For many people, 3D printing is a very new technology which they only discovered recently. However, the for some surprising truth is that 3D printing is a rather old technology. One technologiy - Stereolithography - was developed in 1981 and patented in 1984. The first program for developing 3D models was available since 1983 meaning it is even older than the World Wide Web which was developed in 1989.[br]In fact, 3D printing is already used for prototyping quite often in the industry. It was just not widely used by end users as of yet.[br][br]

In the year 2009, the patent for the Fused Deposition Modeling technology expired. As a result, enthusiasts especially from the field of mathematics started to develop cheap versions of machines using this technology. The now cheaper machines lead to a dropping of prices from 20.000€ and above to only a few hundred within only a decade for really affordable machines.[br]Other patents expired in the last years allowing more affordable machines as well.[br]Not only did prices get more affordable, also the technologies themselves developed and gained better quality by the advent of using 3D printing for the quick production of items or prototypes. And as 3D printing is now more in the focus, more interesting fields like sophisticated materials or new fields of usage open up.

Technologies can be cathegorized by their used materials and the way they add each layer of material to existing hardened material. Materials cover powders, liquids, endless filaments, granulates, and more. What they all currently share: a layer of material each is hardened and fused with another layer of material until an entire item can be taken out of the machine.[br][br]

The 3D printing technology which is very affordable and widely available is FDM or FFF which works basically like a glue pistol adding material layer per layer through a nozzle. The technology was developed by S. Scott and Lisa Crump who were part of the company Stratasys. The company Stratasys still holds the patent of the name FDM, thus the RepRap movement - a group of enthusiasts with mostly a mathematical background - created the name FFF which can be used without constraints.[br]This technology uses so called thermoplasts as material. A thermoplast is a material which melts when heated up, is then squeezed through a nozzle and afterwards hardens when cooling down. Often, those [br]thermoplasts are sold as filaments, long strings without any end in one color. [br]As explained before, each melted layer hardens in order to allow another layer to be extruded on top of the old layer. The precision of this technology relies heavily on the layer thickness and the nozzle diameter. The smaller both is, the slower but more accurate the production process is. FDM needs support material for overhangs usually bewtween 30 to 40 degrees.[br]Colors of FDM printed items have the color of the filament used. Most printers use one filament and thus produce items in one color.

Developed in 1981 and patented in 1986 by Robert C. Hull, the oldest 3D printing technology uses a material that hardens when exposed to UV light by eg. a laser and is usually a photopolymer - resin is often used today as a material. This technology allows a very high precision. However, it needs to be postprocessed since the sun emits UV light leading to an ongoing hardening process turning it brittle over time. [br]Hull also developed the STL file format. The items produced have the color of the used photopolymer which is usually one color but since it has to have a coating due to the UV hardening, it can be colored afterwards. A variation is spraying photopolymer as droplets through a nozzle hardening the material directly afterwards using a UV lamp. This technology needs support since it is either produced within a liquid or [br]into air.

This technology uses a powder, often a variation of Nylon and thus a bit flexible but still very robust, which is applied in layers in some kind of building space, heated up until right before melting together and [br]then shot at by lasers to heat up the material all the way up until they sinter or melt together. Afterwards, the material has to cool down and then can be dug out of the remaining material like a geologist would dig[br] out items from dust. Material only comes in Black, White and variations inbetween so usually, white material is print and the objects are then dyed to achieve colors. Support is not needed since below each layer of material is an existing powder layer of material.

Just as SLS, Binderjetting uses powder as material, usually gypsum or ceramics but also metal is possible. The material is added in layers, afterwards glued together and then the item is dug out of the remaining [br]powder just as the SLS process - only without a cooldown phase. Furthermore, support is not needed and the majority of unused powder can just be reused.[br]Since the glue can be colored, this technology can produce colorful items.

For ptinting 3D models, you need a 3D model, a [b]slicer [/b]that cuts your 3D model into slices, and a 3D printer.[br][br]The 3D model has to be watertight with walls that are thick enough to withstand the laws of physics and the file size should be at least below 30 MB, the smaller, the better. Also it needs to be smaller than the building space of your printer - otherwise, you need to cut the 3D model into smaller pieces.[br]This 3D model needs to be turned into so called G-CODE which is understandable by your 3D printer.[br]

Software exists that lets you connect to a printer directly.[br]Usually, a 3D printer comes with a slicer that was set to operate your type of printer by the manufacturer. They often have more than one 3D printer model they offer so sometimes, you might need to check the manual which printer you should choose.[br]Major pitfalls: installing a language you do not understand (even more careful with letters you can not read) or selecting the wrong 3D printer from the manufacturer.[br][br]But there is also [url=https://www.geogebra.org/m/hdqxz2vj#material/hxhz33bg]software that has common slicers implemented[/url] and can operate the printer by manually setting the options. Careful! Using this can be quite cumbersome but gives you a lot of control you would not have otherwise.

Starting and stopping the printer depends on how you connect to it. [br][br]Usually, you take a storage device like an SD card or USB drive, slice, save the resulting [url=https://reprap.org/wiki/G-code]G-CODE[/url], go to your printer, insert the device and press "print" there. Please read the manual of the printer for this.[br][br]In our case, this is either done directly on the printer if the 3D model was stored on an SD card or indirectly by Repetierhost. After slicing you can choose to either save the G-CODE to your computer or to an SD card or to send it directly to your printer after pressing "print" in the Print Preview.[br]But do not be impatient, the nozzle for melting the filament needs some time to heat up. After the heating, the print will start automatically.[br]

Also, the printer will stop automatically after your print is finished - no manual stopping needed.[br]In case of a bad print you do not want to finish you can stop the printer at "Manual Control" but it will not stop immediately to print. There are a few lines of G-CODE that are stored ahead on the printer to help overcome communication troubles with remote sources like your computer that will be carried out.[br]In case of any emergency it is best to not stop the printer but remove the power plug.[br][br]Always keep in mind that the nozzle is very hot to be able to melt the material!

The currently common file to save 3D models is STL - an abbreviation for StereoLitography. The company 3D Systems created this to be able to describe three dimensional objects.[br]An STL file contains triangles and a normal describing where the upper and the lower side of the triangle is. We call these triangles faces - they have one outer and one inner side.[br]The more triangles an item has, the larger the corresponding STL is.[br][br]Other formats describing 3 dimensional items also exist which provide additional information to just the geometry and whether a face looks inwards or outwards. Other formats like OBJ allow saving colors of faces or information about the roughness of the surface. But these formats are less common.

To have create a model that is 3D printable, some certain cirteria have to be met.[br][br][b]Enough walls[/b][br]Most importantly, it needs to be a whole item.[br]Whole in this context means that it should not have open sides. We call this watertight. In short, this means that it needs to be compact and must not have holes where water could run in. Since all sides of a 3D model for printing have insides and outsides, all outsides should face outward and all insides should face inward.[br]This can be compared to for example a thermal or vaccum flask keeping your tea warm. It has an outside wall and an inside wall where your tea is inside kept warm. In case there are holes in the walls, the tea can leak into the thermal flask.[br]In case you draw something virtual, it can easily happen to forget that things in the real world have outsides and insides, even very thin things like a sheet of paper has a thickness as everything has in the real world. In case you forget sides, we can not get your item into the real world without repairing it.[br][br][b]Thicknesses[/b][br]A walls thickness should never be below the printing nozzle or minimum material grain size. Also it should be thick enough to withstand whatever you think it should be used for. In case you create thinner walls than what physics and material gives us, the machine will try to fullfil your wish by making unexpected things during printing.[br][br][b]Always separate walls[br][/b]Intersecting walls are no problem as such, most software can handle this. However, intersecting walls are no good news. It means that two walls are stuck into each other which you can do in a virtual environment but in the real world, sticking things into each other like needles into fabric creates holes. In the virtual world, it is just two objects in the same space. Try to avoid this, it can cause calculation errors and lead to quide unexpected results.[br][br][b]Filesize[/b][br]The more faces a model has, the larger the file that is loaded into the printer. Often round shapes have many faces. However, large files can be a problem for the printer software or the computer that generates the information so the machine knows what to do. Please try to keep the file size under 30 MB, about 5 MB would be optimal.[br]The larger your item, the longer the calculations will take and the more errors may occur. 3D slicing (cutting your item into slices that are printed one after the other) is a complex mathematical process, and the more data you have to calculate, the harder it will be for the computer to calculate it. So, for example, avoid things that are unnecessarily "round". Round in the sense of: Every 3D model is usually made up of triangles, and since round shapes are only ever mimicked by angular things that triangles just are by definition, it is not necessary for your object to be rounder than a human can see or perceive as round. So keep it to a resonable minimum.[br][br][b]Connected walls[/b][br]Sometimes it happens that models are created that to not combine the parts of the model into one single model. Thiy can often be handled by printing softwares but it would be the equivalent of you putting on clothes. They are not really part of you, just on you. This can confuse machines sometimes.[br]Thus, a proper 3D printable file should have all parts connected to be one single and complete shape - like your skin is totally attached to you.

In case you would like to create your first 3D model, you can use a wide variety of software to do that. They all have a different focus and you can choose whatever tool suits your task best.[br][br][b]Tinkercad[/b][br]Very easy to use is Tinkercad by Autodesk (free to use) that also allows you to learn about basic 3D model creation and even produce your own lectures. When working with this tool, make sure you always look at your working area from multiple sides. Since screens are flat, it is hard to detect where in a three dimensional environment your object actually is. There is also a way to collaboratively work on a project simultaneously.[br][url=https://www.tinkercad.com/]https://www.tinkercad.com/[/url][br][br][b]GeoGebra[/b][br]GeoGebra allows users to create objects using mathematical equations or formulas. In case you already have an account, you can use this feature. If not, we encourage you to check out GeoGebra which focuses on aiding teachers primarily in the STEM area and of course it is also free to use.[br][url=https://www.geogebra.org/]https://www.geogebra.org[/url][br][br][b]OpenSCAD[/b][br]Another free tool that is widely used by teachers and students with a more intense background in informatics is OpenSCAD. Here, you basically program your 3D design. This is often the choice for generating items with varying variables like a generator for bracelets that makes different shapes every time you run it.[br][url=https://www.openscad.org/]https://www.openscad.org/[/url][br][url=https://www.openscad.org/cheatsheet/]https://www.openscad.org/cheatsheet/[/url][br]Examples on Thingiverse are available! Most customizers are done by OpenSCAD. [url=https://www.thingiverse.com/thing:1485673]https://www.thingiverse.com/thing:1485673[/url][br][br][b]Google SketchUP[/b][br]There are free and proprietary versions of SketchUP. Some improved versions are also free for schools after registrations. As Tinkercad is, this tool needs a connection to the internet since it relies on the cloud. Since also 3D printing is supported, it comes with some basic shapes just as SketchUP does.[br][br][b]Blender[/b][br]Far more complex but still free is Blender which was not primarily a tool for generating printable 3D items but for creating 3D models for computergames. The vast array of different settings can be very confusing for beginners. However, working with Blender has many advantages when it comes to evaluating your 3D designs physical attributes.[br][br][b]Fusion360[/b][br]This tool is free for academic use but costs in case it is used in a proprietary environment. Using this tool, we are back in the array of tools from Autodesk. Again, this tool contains an array of different options that can be confusing for beginners. The focus of this tool, however, was not creating items for computergames but designing CAD drawings. It is thus widely used by people who both want to learn about CAD and 3D modeling.[br][br][b]FreeCAD[/b][br]FreeCAD is a relatively simple to use CAD drawing program that also allows you to export STL files which you can use for printing. This tool is free as the name indicates. Since CAD drawings are not per se meant for printing, it is advised to have the resulting STL repaired before printing.[br][br][b]Rhino[/b][br]Very commonly used by 3D designers is Rhino. A licence for 30 students varies between 400 and 1000 Euros.

Existing objects can be turned into 3D objects using some sort of scanning it.[br]Usually, this is done by a process called photogrammetry where many pictures of all sides of the object are put together to shape the object. For this, it is necessary to have as many pictures as possible from the same distance to the object. Otherwise, details could be interpreted as too big or too small that they really are. Also, the objects should always be very well lit so all details can be visible on the images.[br]The pictures can come from scanner systems which usually come already with the software putting together the object or from other sources like extra scanners, cameras, or smartphones. However, often they need extra software which can cost alot additionally.[br]Scanning with smartphone apps often costs per data export or have a monthly fee and a good scan needs some experience in moving the smartphone in exactly the right distance at the best speed around the object.

There are several approaches to checking a 3D designs printability and repairing it in case it has the need for improvement.[br]One very simple solution - in the case of already having an Autodesk account due to using TinkerCAD - is the Netfabb online service.[br]Simply upload your 3D design to https://service.netfabb.com/login.php and get them back as repaired as possible. This service connects walls and closes holes.[br]However, to avoid unexpected results, check your file before you press the print button once more. Sometimes, repairing can have unwanted side effects.

The research in the field of didactic indicates that the implementation of 3D printers in the classroom increases the students digital competence, the teachers digital competence, the creation of[br]assistive technologies, and improves collaborative learning between the students with disability and students without disability. In this project we deal with the implementation of 3D printers in inclusive education as well as using 3D printers as a tool for collaborative education for students with disability and students without a disability. [br][br]Implementation of 3D printing in special and inclusive education can have the following benefits: flexible and adaptive methods of presentations, as well as engagement, different types of expression and perception which could be adapted to different abilities.[br]The big advantage of implementing 3D printers in education is: [br][br][list][*]they are getting easier and easier to use[/*][*]they allow teachers to produce and adapt material for students (Wonjin et all. 2016). [br] [br][/*][/list]In special and inclusive education 3D printers could be used to teach students with disabilities like motor, cognitive, and visual impairments, as well as in combination of these three disabilities (Ford & Minshall, 2017).[br][br]

Motor impairments such as quadriplegia, cerebral palsy, neuropathy, or muscular atrophy usually require different assistive tools and technologies to allow people the solving of educational as well as everyday routine tasks. 3D printers can be used for the production of different types of assistive tools to support the learning experience of students with motor impairments. One example was presented in the study of Buehler, Kane, Hurst (2015) where a stylus grip was developed and produced for students which have limitations grasping items by using a 3D printer. In their work they created a model which helped their students by the following steps: [br][br] 1. They had a student grab clay as the student would grab an object[br] 2. The clay formed by the grab was 3D scanned and turned into a 3D model[br] 3. The 3 model was print using a 3D printer[br] 4. The print was covered by rubber using an aerosol spray to soften the texture[br][br]Afterwards, it was usable by the student.[br]The student was asked for an opinion on the assistive tool. By the opinion of the student the model which they printed with 3D printers was more suitable then other silicon or rubber models which the student had already used. Some of the rubber models were even rather expensive, worth more than 150 $. Researchers Hofmann, Harris, Hudson, Mankof (2016) conclude that 3D printers could be used as tools for printing different types of models which could be used as assistive tools for people with limited upper limb movement. One of the major advantages of digital fabrication for people with disabilities is that it is computer controlled (xx). With appropriate accessibility software/hardware, a disabled person can do things that they would be physically unable to do using traditionally fabricated equipment (Hurst &Kane, 2013).[br]One example of a 3D printed model which was printed by the author of this paper is presented on the photo 1. The aim of this 3D printed model is to help students with limited grasp abilities to hold a pencil in order to write as well as to simplify tipping on keyboards. [br][br]https://www.thingiverse.com/thing:1058000

The implementation of 3D printers and 3D printed models in education can have positive effects on technical, communication and collaborative skills of students with cognitive disabilities as well (Buehler, Kane, Hurst 2014). Buehler et all. (2014), indicate that the implementation of 3D printers in formal and informal education can help students with cognitive impairments to improve their ability to work with computer files, to search for resources online, and to write e-mails, as well as practice spatial reasoning. In the same research they suggest the preparation of notecards with instructions which are supposed to help the students with cognitive impairments to access data. Results of the study (Frauenberger, Spiel & Makhaeva, 2019) indicate that the implementation of new approaches in education or communication with student’s with cognitive impairments should be related with their previous tools and experience.[br] The research in this are indicate the implementation of digital fabrication in education of students with cognitive impairments is combination their everyday activity, scanning, and printing, in the collaborative process between disable students, educators and pears (Frauenberger, Spiel & Makhaeva, 2019; Taylor & Hurley 2016). With implementation this rolls the researchers Frauenberger, Spiel & Makhaeva, 2019 are successfully create several 3D models with a 8 years old autistic student. Huge number of paper indicate the combination of 3d printed models in education of the student with dyslexia can help them in diminution of their effects. [br]One example of 3D printed model which printed by the author of this paper as presented on the photo 2. The aim of this 3D printed model is to help to students with dyslexia to concentrate in the one or two sentence during the reading. [br][br]https://www.thingiverse.com/thing:2802065

Visual impairments are one of the disabilities which allow a lot of possibility for implementation of 3D printers and 3D models in educational purposes. With 3D printers could be printed learning models, graphics from different teaching subjects. With implementation of models in education of blind and visually impaired can be increased their interest for learning STEM content in the school, because they have possibility to sensually explore the teachin contend (Similarly, Kane and Bigham, 2014). Result of the researchers Giraud, Brock, Mace, Jouffrais (2017), indicate the visually impaired students which teaching content from geography and history with implementation of 3D printed models has a better spatial and textual knowledge from this subject then a students which the same content learn with implementation of raised line maps printed on swell paper. This results are in the line with results of other researcher which conclude the small-scale models which could be 3D printed are an good alternative to RLMs for acquiring spatial knowledge in the absence of vision (Picard and Pry 2009; Brock et al., 2015; Giraud et all 2017). Implementation of 3D printed models in education more than other textual and hearing methods increase visually impaired person’s memory, imagination and desire of learning, because 3D models provide them sensual perception of learning content (Wonjin et all. 2016). The same researchers conclude the 3D printers provide possibility for the teachers to print schemes, graphs and picture from the books and on that way create tangible materials for visually impaired students Stangl, Kim, & Yeh, 2014). [br]On the photo 3 are represented Braille Periodic Table of elements which could be used as better understanding chemical content. All chemical elements at the model are market on Braille letter. [br][br][br]https://www.thingiverse.com/thing:59275

In case the print does not look like it should, it might be that set parameters do not work optimal with the material- machine- 3D model combination.[br][br]You can find a lot of solutions here: https://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide[br]And similar or more here: https://www.simplify3d.com/support/print-quality-troubleshooting/[br][br]Often it helps to just reduce or rise the printing speed.

The printer does not print right away since the material needs to be heated until the melting point. Only afterwards can the print begin. Be patient.[br]In case you see the material dropping and still nothing happens, make sure your slicing process was done properly. Go through your sliced file slice by slice and check if all is ok.

After the print is done, a little waiting period until all has cooled down is highly recommended. The print will get a bit more loose from the surface and can be removed better. Furthermore, keep in mind that the nozzle is really hot and also the print bed can get hot. So better not use your fingers for anything, use spatulas or ice cream sticks or chopsticks.

In case of any emergency, do not hesitate to pull the printers power plug. You will not be able to redo the print perhaps, but better a print gone than your fingers![br]After pulling the plug, do not forget that all parts are still hot. Also, they need to be heated up before commencing the print again.

In case your object gets loose on the glass plate it is printed on, we have a nice trick for you: use hairspray on it![br]Hairspray is a bit sticky and helps keeping your object in place. Also, it is very cost efficient and you can wash it off your print if you want to.[br]However be careful, cans containing hairspray can explode in the heat and are also flammable so do not store the cans in the sun or near a fireplace or heater. Always store it in a dark room. Use it at your own risk.