I just had an idea about how to turn a standard unicycle into a giraffe using all the existing parts except the cranks. Made a sketch of my idea, blue is the existing unicycle parts and red is the addition.
It is basically the top part of a Nimbus performer put on a standard unicycle and a couple cogs put onto the ends of the axles. Seat, seatpost and pedals can be migrated upward. It is sort of cool because you could use any wheel size for this.
There still needs to be some kind of chain tensioning device but there are many ways of doing this.
Just another project that I may or may not actually get around to making.