Gordie I take and drill two 2mm holes about 1 1/2 inches apart and then remove the wood between either with a spiral blade, knife , exacto saw or dremel. To ensure that the customer always gets a clean looking coin slot I will sometimes take a 2 1/4 inch long .025" thin 1 inch wide brass plate and with a jeweler's blade cut a coin slot in the brass plate then fasten that down with the same screws I use on the windows. That brass plate can cover a multitude of bad cuts
DW
DW