: The problem is that is it twisted, it will probably continue to do so for a
: while and will likely be unstable during temperature and humidity changes.

Hi Brian,
The twist itself isn't a major problem, it's future changes that are problematic. Hence "You can still use it if it stays twisted and stabilises" in my post. Once it's as stable as it gets, painting or varnishing should help keep it stable.

Even a straight beam will change slightly with humidity. That's what sight-lines were invented.

I prefer ply box for beams I want to stay shape stable. If you make the beam as a truncated triangular section, it will be more rigid and resist twist a bit better. This shape might not be great with internal strong-backs.

Mike Savage
South West Cork