it seems like I am frequently trying to prop things up on the bench or mill, and fumbling around to do that. I have some classic mill jack stands, but they are kind of dinky and unstable. Plus, I just made a LH internal threading tool, and wanted to try out the away from the headstock turning and counterclockwise rotation for both upside down external threading technique and backside internal threading. So this was a practice project.
I made three adjustable steel stands, 2.25" in diameter. The half sections screw together with about a half inch of vertical adjustment. I played with my dividing head to mark off 5 thousandths of vertical adjustment between tic marks, and used different thread pitches as more playing around. After struggling with the first stand, trying to get a custom (and random choice of) pitch diameter to thread together smoothly and without slop, I spent an hour with Machinery's handbook and targeted 2"x 10 TPI and 1.75"x20 tpi. You end up with toleranced targets for the turned external OD and bored internal ID, either class 2 or class 3. Now the threads feel smooth without excess slop.
So it was educational, and even perhaps I'll use these someday. I am thinking if I need to support a piece on the mill table for through drilling, these would let me level it pretty perfectly and then clamp it down on these with the mill hold down rods.
Oh, I also sunk some rare earth magnets into the blocks for stacking and using them on the arbor press. The magnets are strong enough to hold the block up against gravity, and recessing them a couple thou below the surface protects them from damage, since they are quite brittle.