Silicone Pull Plugs
While tapered plugs are fantastic for blind holes, silicone pull plugs are just as great for through holes. Pull plugs feature a larger handle, making them easier for installation and removal. These pull plugs are great when your main task is masking the bore threads if you need to mask the leading three or chamfer, or if you are concerned about shadowing, check out the chamfer pull plug below.
When ordering these, you'll want to get a plug that is slightly larger than the inside diameter of the hole you're masking.