You can use lots of things for the hole making!
With certain rubbermaids they may be soft enough to just use a screw and screw driver. this takes awhile though! A drill works good.
If you dont have a drill or whatever you can use a screwdriver thats heated up and melt the holes. What I do is melt the amount of holes I think it will need, within a couple days you'll notice if you don't have enough because the cage will have condensation on the insides....I drill more if thats the case, wait and if its enough, great....if not more holes. lol.