I put a switch and a couple exra inputs so I can dial between CD and LP. You can make an 'almost round' knob like mine by cutting a X" square, drilling the center hole and tapping threads for the set screw. Then trim the corners to make an oct'n, insert a bolt in the center hole, chuck it in your drill (still with me?), clamp the drill in a vise, turn the drill on and then (this is the best part!) carefully hold a belt sander with 60 grit to the spinning block of wood. Trust me! It works! Go ahead and use the hole saw and fill the visible hole with 12 or 10 gauge copper wire. Looks good. You can buy hole saws that have an arbor attached but no center bit. They're not meant to be used w/o a center bit, but, only in a drill press with the work securely clamped you can. My knob is Cocobolo and the indicator on the knob as well as the 2 positions are marked with 10 Ga. wire. Looks good with a cheap digital camera.