I built one very similar to this but did not want thumbscrews. So I simply made the cones "stepped" to fit my Husky and KTM wheels. I also simplified the mounts. I used 1/2" drill rod and 1/2" shielded bearings. It's very accurate. If you don't have a lathe, you'd have to have a machine shop turn up the cones. I tried it once with sealed bearings and they have too much resistance. Shielded works great.
Here's a pic I found of the dead on rails.
I drop mine down on jack stands, takes seconds to set up. Mine is pictured with the KTM cones on it which are 20 & 26mm I think. The Husky ones are setting next to it. I also made some housings for the bearings but they serve no purpose.
Total cost was maybe $20.
Here's what I used, Mcmaster catalog stinks for linking parts, but I listed the part numbers.
Tool steel 0.5000" ±0.001" 8893K451 $5.06
1/2" ID 1 1/8" OD double shielded ball bearings 6384K61 $7.98