I think I was using 1/4 inch, but just a suggestion from someone with a little experience ... try using a soldering iron instead of a drill. I've cracked a butt load of rubbermaids in my life by drilling and it leaves little shavings everywhere. A soldering iron can be picked up at radio shack for like $6 and it melts perfectly smooth little holes much faster than drilling.

And besides, melting the holes leaves that smell in the air that i used to love as a kid ... you know, from melting those little green army men when you play war! ... LOL ..... :mrgreen:

Hope this helps.

-adam