Here’s a cool instructable on how to make your own banana bike. Although I’d probably never recommend you ride one, it’d be fun to build one yourself.
Convert a small kid bike into a fun sporty looking silly riding adult bike.
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.