A solid rest with no slopiness in the adjustments doesn't necessarily have to be made from machined steel/aluminum and cast iron.
This is a rest that I made from oak, adjustable for windage and elevation. It is solid as a rock, and has no slopiness in the adjustments.
I used a prototype of this rest to win first place in the sporter class at a rimfire benchrest match at the Riverside Gun Club, Richfield, nc a couple of months ago. I shot a 990-29x using a stock CZ 452 Trainer and SK standard Plus ammo. I would have done better, except that on one of my cards, I had set my timer for 10 minutes instead of 15, and at some point I looked at it and thought that I only had 1 minute left to shoot 15 targets, so I just sort of blasted the remaining targtets, and dropped 6 points there.