Kids outgrow their bikes so fast but here is a way to put even the smallest 12" wheel kid bike back into action as a cool-goofy adult bike.
Re-uses/repurposes old items from the dumpster:
small kid bike,
old steel tube,
wood mop handle.
Visit a good primer on Dumpster Dipping
Only had to buy the banana seat and a 5" long 1/4" bolt.
Step 1: Parts Needed
Steel tube to fit in steering tube and support seat nose.
Steel tube that accepts kid bike stem
caster wheel from cart, furniture etc to form swiveling seat nose bracket
1" or 7/8" wood dowel (about 8" long) to connect caster threaded post to steel seat nose support tube.
Crutch to support back end of seat
3/8" bolt to bolt seat nose to caster bracket
1/4" by about 5" long bolt and 5-6 nuts to bolt seat back to crutch