A stylized push plane with spinning propeller.
It's grandkids week at our household so I designed and printed an airplane push toy as an addition to the butterfly push toy (http://www.thingiverse.com/thing:1027577). Our Makerbot Replicator 2 is running overtime printing these things in a variety of color combinations.
Video of prototype is here: https://www.youtube.com/watch?v=pKn8SvAMDXQ.
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 22.214.171.124 "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 inside the appropriate holes hold the wing and chassis pins to the wings and chassis respectively. Small dots may also assist in holding the fuselage sections together.
Apply a small amount of light machine oil to the axle and gear surfaces.
Comment if you have questions.
You fail only when you decide to quit learning.