Spanner wrench for use with the lock nut on the ball screw kit from CNC Fusion. I cut one of these from the bottom of an aluminum frying pan. It works great for tightening the ball screw lock nut on my X3 CNC mill.

I designed this wrench so that it can be cut from a sheet of material using a 1/8" endmill cutter. I cut mine out using a 1/8" Dremel bit rather than an endmill because that is what I had on hand.