Hi,

Having read some of the references you folks directed me to, I think
I've eliminated some options. I'm going to either use:

- exterior grade (ie CDX) or high density overlay (HDO) plywood, with a
coat or two of quality epoxy, and make a 5'x7'x3' box.

I don't think I'd even glass it, just caulk the seams and put a liner
in. One problem with this method is that if I used 4x8 sheets of
plywood, the 5'x7' bottom would have to have a horizontal seam. I'm
guessing I'd spend $150-250, plus the liner.

- cold-mold a tub with more comfortable contours and curves, using 3-5
layers of approx 1/8" fir (because I have an enormous free supply)

I've read in an article (not sure of the date) that cold-molding cost
about $3.30 per pound, at 1 pound per square foot, including the cost
of the wood. My tub would be about 107 sq ft. So by that person's
calculation, it would cost just over $350 for the raw materials. I'm
wondering how much of that cost was due to the wood, and how much for
the epoxy. I have a good amount of free time, and would love an excuse
to learn this method, so labor isn't an issue.

- I've heard that there was an article in Home Mechanix (somewhere
around 1990, I haven't found it yet) that described plans for building
a tub by fiberglassing over masonite (hardboard). Sounds interesting,
but I'd like to find the article first. Masonite is very cheap, and
that "supply of fir" I have includes 2x4's, which could be used for
additional framing.

Thanks for the continuing help.