While writing a comment on a different community, I figured I would post my homemade plate-bearing pegs here. These were made for my Body Solid BFFT10R functional trainer's weight stack, to allow loading 50 mm Olympic fractional plates.

This first one is a simple wooden peg made from a scrap 4x4 block, turned on a router -- because I don't own a lathe -- and with a threaded rod (3/8-inch; 10 mm) through it. The rod is mild steel, but that caused some minor bending when loaded with a 15 lbs plate.

So for my second and more permanent attempt, I attached two back-to-back pegs directly to the weight stack's center point, using a Grade B7 threaded rod, in lieu of the original bolt that was there. This helps keep the weight stack balanced front-to-back, makes it run more smoothly, and there's a reduced risk of the plate slipping off.