Chapter 2 – Let’s Print Something

Quick Links

Online Repositories

When I got my printer I had almost no experience creating 3D models. This didn’t stop me from burning through 2 kg of plastic, however. I printed a lot of models from the Thingiverse, an online repository of user created objects. The Thingiverse was the first and is probably still the most famous site set up for people to upload and share models for 3D printing. It was started by Makerbot and probably did more to sell their printers than anything else. One of the powerful aspects of the Thingiverse is that users are encouraged to put a Creative Commons license on their models so that others can build off their models and create even cooler stuff.

Today there are many different online repositories you can use. Some of these only have free models and some offer paid models. A Google search will easily find many different sites. Some of these arose after the online community became upset at changes in Makerbot and/or the Thingiverse site and so they left Thingiverse. Despite the changes the Thingiverse remains my favorite place to get and share 3D models. So I recommend checking it out before dismissing it out of hand.

I should also mention that some 3D models you find online were never intended for printing. Many were simply made to be displayed on computer screens or used in video games. Some of these may be printable, but many include fine details that could never be reproduced properly on your 3D printer.

The Smithsonian also has started its own online repository for 3D models. Basically, they’ve begun creating high resolution scans of some of their artifacts. They share these online for study. Many can be successfully 3D printed. Our AP US History teacher is a big fan of Abraham Lincoln and was very appreciative of the Lincoln life mask that I printed for him. So far the archive is relatively small and many of the artifacts are not suitable for printing. However, there are some remarkable pieces in there that many teachers would love to have.

One of my new favorite repositories is MyMiniFactory. MiMiniFactory will only publish models that they themselves have printed. So you can be assured that if you download a model that it will work the way the designer claims it will. However, this is not what caused me to add MyMiniFactory to my list of go to sites. They have a project called Scan the World. As of this writing they have over 3,000 models that have been scanned (and successfully printed) from museums around the world. There are some amazing artifacts here that any history teacher would love to have on hand.

There is something magical about holding an artifact while you learn about it, even if it is just a printed copy. This was first made obvious to me when I listened to the RadioLab episode about the Taung Child. In the episode they talk about a fossilized skull and the story behind it. Then then reference the Thingiverse model of the skull. Being able to hold a copy of the skull while they discussed it was pretty awesome. Even though it was a fairly low resolution duplicate, having the skull in my hands helped bring the story alive in a way that did not happen when I could only see a picture of it on a screen.

In the same vein, I have a feeling that having a copy of the Lincoln life mask from just before his presidency and being able to compare it to the mask from near then end of his presidency could be a very powerful experience for students.

Introduction to Tinkercad – Time to make your own thing

When I got into 3D printing I had virtually no experience with 3D modeling and my school lacked any CAD software. As it turns out you can get free professional level software from AutoDesk for education. I considered this, but ultimately decided against it. If I want to use 3D printing with my students they would also have to know how to use this software and for one off projects in physics or electronics this is not a reasonable expectation.

Enter Tinkercad. Since I started using Tinkercad it was acquired by AutoDesk. AutoDesk has made it totally free to use. There is also a paid version, but it doesn’t really add that much so you can use the free version for yourself or with your students. Most of the models I’ve created were made in Tinkercad.

There are some tutorial lessons available in Tinkercad, in fact as soon as you join and login you will be dropped into one. I generally don’t have my students go through these initial tutorials. Instead I give a little instruction and then have them play. The instruction is typically no more detailed than the video above.

Once students start to play they come up with more questions. These are typically questions that I would have answered in a more in-depth lecture. By allowing students to discover problems on their own I find them much more receptive to instruction. Typically after helping one student with a particular problem they will help when their classmates run into the same problem.

Make an accessory for your Cell Phone – Student Project

One project I’ve done with my students was to make an accessory for their cell phone. I tend to give very scanty directions so that students have a maximum room for creativity and problem solving.

Project outline:

      1. Day 1 – Introduction to Tinkercad:
        • Quick lecture 5 min or so, then tell them to make something cool.
        • This day is about playing with the tool.
      2. Day 2 – Introduce the Project and Brainstorm:
        • Today is about thinking and creating simple sketches.
        • Students in groups of 3ish should come up with 3 ideas with concept sketches.
      3. Day 3 – Prototype an idea:
        • Students pick one of their ideas (may need some guidance from teacher).
        • Attempt to create it out of cardboard and tape
      4. Day 4 – Refine and begin design in Tinkercad:
        • Refine idea based on prototype.
        • Make all necessary measurements of phone and prototype.
        • Think about production: Size? Amount of Material? Print as one piece, or multiple pieces? Best orientation for strength and least support required.
      5. Day 5 – Finalize Design and Print:
        • Finalize design in Tinkercad
        • Print and Evaluate
        • Repeat steps 3-5 as needed

Depending on a number of factors you may need to adjust the schedule as outlined above. You may also want to place some limits on the maximum size and/or amount of material you will allow. There are two main reasons for this one is the to keep the total cost of the project in the reasonable range. While plastic is nit very expensive there still is a cost. More importantly, however, is the printing time required. From my own experimentation I’ve found that if you double the size of an object you quadruple printing time. So shaving off 25% size/material you can cut your print time in half.

Below I’ve included a step by step procedure for creating a phone stand. This is intended to give you, as the instructor, more familiarity with Tinkercad. It is not something I share with my students. I also have a quick video walkthrough of the same thing.

Modify a Phone Case – Student Project or Fund Raiser

Phone Cases

One very easy way of getting students excited about 3D printing is letting them print their own phone cases. Designing your own phone case from scratch can seem a bit daunting. However, taking an existing design and personalizing it is really very easy.

You can do this with your school logo or with designs you find on the internet. Once done students can use them on their own phones or even sell them as a fundraiser. If you plan on selling your designs then I very much recommend you use only your own designs or use public domain or creative commons designs. It is important to remember that both the 2D image and 3D phone case you use will have their own usage limitations.

If you want your design to be a hole in your case as pictured above you will need to select a very high contrast image. Think black and white. This means only black and white, no grey. The black will become the cutout in your case. Also think about if there are parts that will not be supported. If I had an “A” for example, the triangle in the top part of the letter would not be attached to the rest of the case.

The procedure is relatively straight forward. You need an stl file for your phone case and an svg file for your cutout. You can import both into Tinkercad. You resize and position your cutout, turn it into a hole, and group with the phone case.

The hardest part is finding a good image and then converting it into an svg file. You can use a program like Inkscape to do this, but I find it far easier to use an online image converter. I can never remember the url so I just Google, “jpg to svg,” and the first hit is always the site I want.

The full procedure is outlined in the Google Presentation below or you can watch a quick video walkthrough I’ve created.