Harold, thank you for your points, and they are a concern. I want 1/4
inch because I feel it will hold up to years of service, particularly
where the fire is actually built inside; the intense heat and,
presumably moisture from the wood or perhaps moisture from humidity
and/or rain seeping into the ashes, seem to cause thin metals to rust
rapidly (I've seen fireboxes that were 1/8th and 3/16th thick that had
*supposedly* only lasted a few years (maybe 3-5). While that's all
loose information, and I've not done any testing to see what kind of
longevity I can get (and any testing would seem to be subjective to the
particular design and environment), the amount of time and effort that
goes into building one of these things (I spent about 10 months of free
time on the first trailer-mounted one I built, including the trailer)
it would be a shame not to build it to a spec that I feel comfortable
with. 1/4" sounds good to me, 3/8" inch would seem excessive but I'll
do that if that's all I wind up using.

Anyway, I appreciate your position of accepting the requirements that
I've set up for this.

--HC