If you have a drill press, buy the tapered plug tool and make your own. Just make sure to use tapered bung plugs so they will stay sealed. Before tapping them in place I used a bit of wood glue on the exterior plugs, then used a sharp wood chisel to cut off the excess, followed by light sanding with a block to smoother the plug. I didn't glue the plugs on interior surfaces. Some bung plugs are just a dowel rod sliced into plugs. I couldn't get those to stay in or seal well, especially if the hole is not drilled properly. I happen to have a broken companion way teak step that I used to make my own tapered plugs. it is kinda fun.