I had an old Shapeoko 2 in my shop that I never really finished assembling. I had the idea to create configurable stoppers so I could perform straightforward cuts, think Etch-a-Sketch with a router.
I was very pleased with the results. The cuts is a bit choppy because I didn’t lock the 2×4 down too well, but for a first cut, not bad. I think I might use this for planing oddly shaped lumber, making rectangular voids in material, and creating simple slots.