Got a set last week for use in the shop. Pentagon Tool has casters with ball bearings in the wheels along with the swivels, which makes rolling easier than bushing type wheels. I read somewhere that they are USA made, but the box I received was from over seas. These were not that expensive, and they do work. I couldn't built them for what I paid for them. I would imagine the wheels might flat spot if someone left a vehicle parked on them for a long time. I have used them by my self several times to gain access to my lift, I would recommend them.
I have never "made" anything, I just modify the things around me into useful items with abilities that were GIVEN to me.