3D Printing and Design

3D printers are iconic makerspace tools for a reason - they are versatile, fairly easy to use, and are fun to watch as they build objects one layer at a time. 3D printing is a method of creating physical three-dimensional objects from a digital model. In order to 3D print, you need three things:

3D Printer
|
Computer with Slicer
|
Downloaded Models - Remixed Models - Designed Models

3D Printers for K-12 Makerspaces

While there are many 3D printing technologies on the market, the most common type of printers found in makerspaces use Fused Filament Fabrication (FFF) technology - sometimes referred to as the trademarked term Fused Deposition Modeling (FDM).

In FFF, plastic filament is softened and pushed through a small hole in a metal nozzle. The nozzle is attached to a robot that can move from left-to-right (X axis), front-to-back (Y axis), and up-and-down (Z axis) over a build surface. The printer extrudes a layer of the model in two dimensions (X,Y) and then moves up a fraction of a millimeter to draw the next layer, continuing until you have a completed 3D object.

FFF printers use spools of thermoplastic filaments that have been specially formulated for use in 3D printing. Some printers require proprietary spools and can print with a varying selection of compatible materials. Filaments come in two common diameters: 1.75mm and the less common 2.85mm.

The most common plastic to use in makerspaces is PLA (polylactic acid), a plastic made from plant starches that is easy to print with, has a low printing temperature, does not shrink or warp easily, produces the least amount of odor, and is available in a wide variety of colors and textures. However, PLA is not very flexible and prints can be brittle and break easily. PLA can "expire" if exposed to a humid environment for too long, becoming more brittle and difficult to print with. It is an excellent filament choice for expressive models, but may not be the best solution for creating mechanical parts.

Another good option is PETG (polyethylene terephthalate glycol-modified). PETG is strong, slightly flexible, and does not shrink or warp. It is not as sensitive to moisture - PET is what most plastic bottles are made of. PETG prints at a higher temperature and usually requires the use of a release agent like glue stick to ensure it doesn't stick too well and cause damage to the print bed.

ABS (acrylonitrile butadiene styrene) is a common plastic used in consumer goods that is strong and durable, but it prints at a higher temperature, smells like burning plastic while printing, and requires an enclosed printer (or very warm, controlled environment) to prevent warping. With PETG becoming more widely available, ABS is less of a good fit for general makerspace use.

More "exotic" filaments include things like flexible polymers, strong carbon-filled plastics, filaments with conductive metal additives, and plastics like nylon are available, but are often more expensive and difficult to work with. Some filaments are abrasive and may shorten the life of your printers' nozzles. Many materials need higher temperatures, heated or specially-treated build surfaces, or an enclosure to print properly. When considering which filaments to use, make sure they are compatible with your printer before you buy!

Less common in makerspaces but increasing in popularity (and decreasing in price) are 3D printers that use Stereo Lithography (SLA) technology. SLA printers use a focused beam of light to harden a liquid resin in layers to build an object. While these printers can produce very detailed prints with complex geometry, the resin used is messy, expensive, and potentially hazardous if not handled correctly. SLA prints need to be washed in isopropyl alcohol before being handled.

Slicing a 3D Model

Once you have a 3D model file, typically in .stl format (short for stereolithography), it must be converted from a 3D mesh into a stack of very small layers that the 3D printer can build. This process is called slicing - taking the 3D mesh and cutting it into two-dimensional paths that the 3D printer will then draw, one on top of another, to create the 3D object. This is done with a program called a slicer. You will need a computer, typically a PC or mac, to run the slicer software.

Once your model is sliced, it is saved as a .gcode or similar file format, and then sent to the 3D printer - often by saving the .gcode to a flash drive and delivering the file to the printer via "sneakernet". Some printers do have network capabilities and most printers can be made to connect to a network with a host computer, like running Octoprint on a Raspberry Pi.

Most 3D printers come with a free, proprietary slicer that comes preloaded with settings for your particular printer. There are other slicers available, and profiles for most machines and materials can be found for most slicing platforms. Many manufacturer- branded slicers are based on one of two open source slicing programs - Cura and Slic3r. Simplify3D is a popular premium slicer that provides extra flexibilty and functionality, but can require more work to get set up for your particular printer.

Finding 3D Models to Print

3D models can be created from scratch using a 3D CAD program, but makers can also find a vast selection of community-created 3D models to download from various repositories on the internet. Those downloaded models can then be modified with a CAD program or just sliced and printed as-is. Grabbing a ready-made model can be a great way to introduce students to 3D printing.

Thingiverse

Run by Makerbot, Thingiverse is the largest and most popular source for 3D printable models. While there are countless models available, not all of them are well designed or even made to be 3D printed.

YouMagine

YouMagine, loosely affiliated with 3D printer manufacturer Ultimaker, is another repository for community shared models.

NASA

NASA shares their collection of 3D models of space-related technologies and discoveries. While not all models are printable, there is a filter that will limit the collection for 3D printing.

MyMiniFactory

MyMiniFactory is a well-curated collection of models that are all printable. This is good source for educational content, including collections of 3D scanned fine art and famous buildings. While there are plenty of free models available, many files require payment.

pinshape

SLA 3D printer manufacturer Formlabs runs this platform for 3D model sharing. There are a mix of models that are good for SLA and FFF/FDM printing. Convenient tags on the model thumbnail indicate if a model can be printed with an FFF/FDM printer.

ALL3DP

Not a repository or collection, 3D printing magazine ALL3DP regularly posts lists and articles about cool printable files.

Creating 3D Models to Print

Downloading existing designs to print can be a fun introduction to 3D printing, but to truly enable students to express themselves or design a solution to a problem, they need access to a 3D CAD program. There are many options, ranging from free beginner platforms found online to expensive advanced professional CAD suites.

Things to Consider When Choosing 3D Design Software

Each software has its strengths and quirks, but it's easy to choose the appropriate software given certain considerations:

Ease of Learning

Some modeling packages
are intuitive and easy to
learn. The cost, usually, is
a lack of certain features,
but this makes these programs a great
introductory tool.

Background Knowledge

Does the user need to be
familiar with mechanical or
artistic design to use this
software?

Cost

3D modeling software
packages range from free
online to downloadable to
several thousand dollar
subscriptions.

Operating System/
Platform

Some packages are designed
on Windows machines and
will not run on Macintosh
unless using a virtual Windows system. Some packages run in a browser, making them suitable for platforms like Chromebooks.

Capability

Can the package create
models at the level of sophistication and complexity
for the desired outcome?

Portability and Output

Consider whether models created in one package can be imported into another for further development.

Free 3D CAD Software

Tinkercad

Platform: Browser-based (Chrome, Firefox, Safari, etc)
Difficulty: Beginner

Easy to learn (and master) 3D modelling platform from Autodesk. Tinkercad also includes circuit simulation and codeblock-based 3D modeling.

SketchUp Free

Platform: Browser-based (Chrome, Firefox, Safari, etc)
Difficulty: Intermediate

SketchUp is great for creating architectural models and designs for woodworking. It can be used to create designs for 3D printing, but has a bit of a learning curve compared to other programs.

Fusion 360

Platform: Windows, MacOS
Difficulty: Advanced

Professional-level design software with powerful features that Autodesk offers for free for students and teachers. Tinkercad includes a "send to Fusion 360" feature that expands creative potential.

Leopoly Makers

Platform: Browser-based (Chrome, Firefox, Safari, etc)
Difficulty: Beginner

Easy to use platform with several ways to model: clay-like sculpting, lego-like block-based building, and lots of preset base models for customizing.

ScupltGL

Platform: Browser-based (Chrome, Firefox, Safari, etc)
Difficulty: Intermediate

Web-based scuplting program for creating expressive models. Sculpting tools can be difficult to understand and creating a detailed model takes considerable time and effort, but it can be fun to jump in and mess around with digital clay.

Onshape

Platform: Browser-based (Chrome, Firefox, Safari, etc)
Difficulty: Advanced

Similar to Fusion 360, Onshape is a full-fledged 3D CAD product development environment. The free version is browser-based, and while there is a learning curve, the tools and features are easily accessible.

Remixing Models

3D models found on sites like Thingiverse can be loaded into a 3D CAD program and personalized or modified rather easily. This can be an easy and fun introduction to working with 3D CAD.