Trust me when I say this, stay away from the dremel or drill and just use a soldering iron to melt holes into the tub. It is sooooooooooooooooooooo much easier. The first rack I built I used a drill, 2nd I used a dremel; then I finally used a soldering iron and haven't looked back. I even have a soldering iron that I use just for melting holes in tubs.