A butterfly push toy I designed for my grandkids, nieces and nephews, but my wife and kids liked it as well, so I guess I'll be printing more.
Video is here: https://www.youtube.com/watch?v=2gHOx2oNcpc.
All pieces are printed with the exception of the wide rubber bands used for traction.
Designed using Sketchup Make 2015, and printed in PLA on a Makerbot Replicator 2 using Makerware 126.96.36.199 "Standard" Settings (.2mm layer height, 2 shells, 10% infill).
Study "Assembly.skp" or "Assembly.stl".
Print and assemble all pieces as shown in "Assembly.skp" or "Assembly.stl".
Test fit and trim, file, sand, etc. all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on the colors you chose and your printer settings, more or less trimming, filing and/or sanding will be required.
Place wide rubber bands around the circumference of each wheel for traction.
Assemble as shown in "Assembly.skp" or "Assembly.stl".
A small dot of cyanoacrylate holds the wing panels in place in the frames.
Comment if you have questions.