These days, most drains are made with PVC or ABS plastic. Plastic drain fittings are usually glued, but the ones you might need to remove temporarily, like cleanout plugs, are threaded.

Once on the rotary tool, the reducer threads into a PVC nipple that is glued to a piece of acrylic. The acrylic acts as the base of the router attachment. Dremel’s official router base is called ...