My thinking is like that also, pipe clamps are simple to make, and
can be up-sized easily, larger pipes and fine threaded bold and nuts
make for real squeezers.
An another way, if you have the room for it, is going the opposite way
from pushing to pulling, a chain and turnbuckle, or straps, metal or
other and turnbuckle, and one can haul things really tight, a come-
along could be used also, it just depends on what one wants to do.

Have fun and take care
Leo Van Der Loo

/SNIP/ as the other stuff goes, I'd think your best bet would be to head
to the hardware store and look at the existing ones and go from there.
By my quick estimate, I don't know if you'll come out very far ahead
of just buying a number of pipe clamps and a selection of black pipe
by making them, but you never know./SNIP/