[DaleHCook]

... you could make one with a cheap standard screwdriver and a Dremmel tool, or a jeweler's saw.

I have done that to make a tool for a specific repair. My Dremel 3000 is my most used power tool. Over the past 35+ years I have assembled a collection of over 100 attachments (grinding bits, brushes, saws, polishing felts, etc.), several accessories (flexible extension, right-angle extension, etc.), and several polishing compounds. For cutting the slot I used a thick cut-off wheel.