I needed a jig/fixture to clamp stock that left the top totally clear and to let me route the edge without any obstructions, & I wanted the edge of the stock needed to overhang the fixture. After fiddling around a bit I came up with a simple jig using a piece of 80/20 (what else?) and a couple 1.5" squares of 1/4" plate. The key to the whole thing is that everything is below the top of the stock so nothing obstructs the router.
The 2 small squares of AL attach the the 80/20 with tee nuts/cap screws. At the right end there is a block of AL that is threaded and a handle to put pressure on the AL square. Both squares are beveled to give them a little bite into the end of the stock. The left square is adjusted by sliding it to fit the stock length.
The right square is left slightly loose on the 80/20, the handle is tightened to press it against the stock, and then the cap screw is snugged down to lock it in place.
Shown here I can route the edge of narrow stock with a slot cutter & nothing gets in the way. It takes less than a minute to swap out pieces of stock.
More fun with 80/20...