yeah i had a dremel but i made over 20 bongs with it my sphere shaped bit, its completely smooth it will only scuff the glass up a bit, i used it way too much

ps. if you use the drop of water on the hot spot trick tape the bottle up with duct tape and scrape off a bit of the tape so your on the surface of the glass like the size of a dime then do it or it will spider crack and you will have a fucked bottle on your hands