i found my old three wheeler some month ago an the attic of my grandpa. apart that is was dirty, the color came of and all wheels where damaged bad, i saw a good project for me.
at that moment i was sure. i will repair it for my little son (2.5 years old).
so i cleaned and sandpapered all partes and made new paint on it but i also designed and printed new wheels for the scooter.
one wheel consist of two printed parts each 120 mm in diameter and 15 mm in width.
glued together one complete wheel has a width of 30 mm and takes me about 4.5h to print.
2pcs. 22x8x7 mm inline skate ball bearings
8mm rod and some parts to lock them in place.
the design and stl’s are downloadable at thingiverse: http://www.thingiverse.com/thing:40413
have fun with it.