I wonder how much difference it would make if I were to
build a loading coil on a piece of 3''x3" wood? It would be
very easy and I could suspend the winding above the wood
form with plastic dowel glued on each corner of the wood.

I could also make a similar coil using PVC pipe. Even in that
case the winding would have a somewhat rectangular form
factor.

It wouldn't be air core considering that it would be over
wood (dry and waterproofed) or PVC pipe.

I do require the structure be relatively strong or I
would wind the coil, put epoxy glue strips along it
to make it like AirDux and the like.

Any comments or suggestions??

Irv VE6BP