I found these plans & thought I'd share in case anyone's in the notion of building one.
It calls for copper pipe but that's a little expensive nowdays so I made one out of 3/4 pvc & braced it inside with metal conduit. Still not nearly as sturdy as a copper one but sure makes taking the cover off much easier.
I'm thinking I got by for less than $15 but I had all tools & glue.

http://www.smithtrust.com/spa/
(I hope this is within posting guidelines)[/url]

Thanks for the plans. I look forward to trying them!

Brian

3/4" pvc is going to be loose as a goose! Wouldn't try it on larger tubs- can probably get away with it on smaller ones

agreed, 3/4" pvc is flimsy, 1" is better, but still not the best for heavier/larger covers. I suggest sweat soldering copper.