Making holes in plastic tubs?

[pitoon]

I'm a herper on a budget here, please bear that in mind when answering! I have a few new tubs...I'm trying to construct a snake rack. My problem is how to most effectively put air holes in them. I have read that drilling isn't ideal as it can leave rough edges, which snakes can hurt themselves on (especially wee ones) and that a soldering gun works well. I tried my woodburner, no luck...borrowed my dad's soldering gun, and once again, no luck. It seems to be just melting the plastic into dome shapes instead of nice, neat holes.

What methods or products do you use to put holes in your tubs? Do you even have holes in them? Can I get away with a slight distance between tub lip and shelf for air? I open each tub every day to visually check each snake, even with more animals I don't forsee changing this habit, so I figure that helps freshen the air in there.

Advice?

Thanks in advance for your time!

you can use a spade bit and a drill or you can use a soldering gun to melt holes.

Pitoon