Very cool. I was looking at these myself. But I ended up buying some great wheels, and will attempt to make something similar. What type of dolly platfrom are you making? My plan is to make a speed rail paltform and a doorway dolly. The wheel assemblies will bolt on (easy on and off) and will be able to be put on either platform. I plan to take the wheels off for transport and storage and keep them in a case for protection. Show us what you come up with.