This is so you can make a larger wheel that can navigate small stairs/steps ... maybe with your robot ... Ideally, each individual OmniWheel would have a motor but this is the affordable solution using one motor driven center gear.

You can snag a 50mm diameter OmniWheel with a 3mm hub diameter out of this for your robot too ... not even use the outer mounting plates.

All these parts are MakerBotable ...

Here's a Demo animation;
brainless.org/MultiMedia/Pictures/SW-Portfolio/StrollerWheelb.gif


This is another of many entries to the makezine.com/go/makerbot contest ...

blog.makezine.com/archive/2010/04/makerbot_giveaway.html

I'm starting to get dizzy from all the dreaming 'n scheming 'n sketching my brains out for this contest.