STL file: http://www.geekhaus.com/makerhome/day27_duckandblock.stl
Tinkercad link: https://tinkercad.com/things/aLiPz8rAjBe-day-27-duck-block-resolution-testers
Thingiverse link: http://www.thingiverse.com/thing:154941
Settings: These testers are built for the Afinia H-Series 3D software, with .3mm fast, .3mm fine, .15mm fast, and .15mm fine. The build times for the individual duck and block are shown on the prints. The print times for each complete tester are the sums of the corresponding ducks and blocks, plus 10-35 minutes for raft and platform, depending on the resolution chosen.
Technical notes: The Afinia 3D software tells you how long an object will take to print before it starts printing, which is how the listed print times on the models were obtained. A filament swap just after the raft and platform finish printing allows the two-color look. It's a pain because you have to pay attention in order to catch it at just the right moment, but it's really worth it for a nice classroom model.
Step-by-step instructions for adding custom text to a .stl model: The difficult part about this print for me was getting the text onto the model. In particular, I wanted to find a method that uses only free software, so that my students would all be able to follow the same method at home and in class. Tinkercad has letters you can add, but spacing them out correctly is a challenge and you only have one rather blocky font choice. You can import .svg files into Tinkercad but it turns out that for some reason Tinkercad cannot recognize text/fonts in .svg files, and that when it does import, sometimes the holes in the letters don't come out right. You can write simple .svg files by hand in a text editor without too much trouble, but Tinkercad won't recognize anything you put in a "text" command in that .svg file. There are online conversion sites for turning .pdf files into .svg, but that seemed to be a pain and I could not get it to work reliably without Adobe Illustrator, which is not free. After much gnashing of teeth and rending of garments I finally stumbled across the following FREE solution:
1. Type the text you desire with the font tool in an Inkscape document.
2. Save the document as an .eps file, and make sure that "convert texts to paths" is checked.
3. Close the file ("close without saving" message is fine; choose that).
4. From within Inkscape, open the .eps file (press "ok" without changing settings).
5. Save again, this time as a "plain .svg" file (not an Inkscape .svg file).
6. From Tinkercad, use "import" to import your .svg text onto your Workplane.
Voilà, we have tricked Tinkercad into accepting our text by making Inkscape wipe out its "textiness" and converting to an .eps path description of the text, then back to .svg format.
