scanker said:What size holes do you mean?
Burner size holes I use a drawing pin and a pair of pliers.
If it's a bigger hole can you drill it?
Bigger still can you cut it with a sharp knife?
If it doesn't have to be circular can you use one of the old style can openers that cuts a triangular hole (the sort used before ringpulls)? I saw these for sale in Morrisons the other day for 49p if anyone's looking for one. They're handy for making windshields or little charcoal burners too.