Here is a C-clamp that I have made. It was forged from a rail road spike.
The screw was made from some old extension bit for a socket tool or something.

It may look as though the wing screw is one solid piece, but the wings were actually inserted into a slot that I cut with a saw and cleaned up with a file. It was then forge brazed using a length of copper wire wrapped around it and borax sprinkled on when it was hot enough to melt said flux. The copper flowed into the seams and now it's a solid and singular unit.