First used the plastic drill bits - sometimes it worked well other times it caught one time fracturing the scrap of plex . Never really seemed to make me feel confident !
Made a little tool with a screw driver welded to a 100 degree machine bolt per the construction manual - this worked great ! after a few trys i found that if I initally punched / melted thru the plex then reheated the tool and finshed with a good hot tool ( red hot) it left a really nice shiny tooling free counter sink !