[Above] Cut the piece of flat steel into two lengths of 3.25 in. Use a file to blunt the edges and round the corners a bit.
[Above] mark a point about 3/8 in. in from each end, centering it on the steel. Drill a 1/4 in. hole at these locations. You will want to use a center punch to give the drill bit a place to catch. The hole is easier to drill if you start with an 1/8 in. pilot hole, then go to the 1/4 in. bit. File any burs.
[Above] Take the 3.25 in. piece of wood, the one you sawed the angle from and drill a hole 1 in. up from the bottom and 1 in. in from the flat end. ith the bolts, nuts, and washers you can assemble the movable stop as shown.
[Above] You need to keep the nuts from loosening on the movable head. Epoxy or a thread locker will work, but I used the center punch to munge up the thread on the end of the screw. Now the stop gets slid onto the bar.
-- Ni faru ion el ligno!