[MrForbes]

In addition the the questions Tom asked about the device, it would help to know what your fabricating abilities are. Having a lathe is really handy for making stuff that turns, but there are other ways to build things that allow you to use stuff commonly found at a hardware store.

One idea would be to put flanged ball bearings in each end of a tube, and put a shaft into it, and use lock collars outside each bearing to hold them in position on the shaft. The tube could be clamped to whatever holds it up, using U bolts. With periodic lubrication, even cheap hardware store ball bearings should last quite a while.