Measure the distance from the keyhole slots to the top of the frame. Foolproof hanging with keyhole slots. Rustic Key Holder Key Rack Hat Rack Etsy Rustic keys Use the slot cutter to cut a vertical slot for hanging pictures with a centered slot. How to cut a keyhole slot in wood . Place the wood on the routing table. Attach a fence to the router to control how long the slot you drill will be. Put the router against the wood, and turn it on. Step 4 put the router against the wood, and turn it on. If you get a good install with the mounting plate, and catch a stud for the screw, it's a pretty strong assembly. #4 · dec 25, 2012. Drill an entry hole larger than the screw head, drill a second hole just large enough for the screw shank, and connect the two by cutting a slot with a saw. Given that you don't have a router handy, this might be a more forgiving way to create the keyhole. Ensure you use a sharp and visible pencil while drawing the slot lines. ...