Drilling a hole at a shallow angle isn’t easy. You’ll probably need to get a long drill bit in order to be able to get the angle without the drill chuck getting in the way. Or else use a small pin vice and drill manually. Best to drill a slightly wider shallow hole first vertically, and then drill into the side of that hole so the drill bit doesn’t slip. And always mask up around the area, as accidents will happen (especially if I’m involved).