While searching on-line for a unicycle, I saw something similar to this. It looked like a fun project and a good addition to our collection of dangerous toys. The kid next door came up with the name. Others called it a unicycle with training wheels.
Step 1: Parts List
3/4" Plywood. A little more than 3 sq.ft.
2x6. About 24" long
1/2 NPT Steel Pipe. 2 pieces @ 8" long.
1/2 NPT Steel Pipe Flange qty 4
1/4-20 x 1" Flat head screws qty 16
1/4-20 Nuts (I used T-Nuts) qty 16
Cost To Build. I had everything except the plumbing parts which were about $18.
Duration: About 2 hours not including the decorating time.