Supermarket flower buckets

I've been looking for the post but can't find it!!!
Stupid question or what?
One of you mentioned cutting the bottom off the plastic buckets (I'm thinking of planting my outside toms - when they're ready of course! - in good compost in them and then in the ground) but I don't know with what to cut them off. They are really thick, aren't they!
Don't mention anything too difficult, I'm on my own!!
Otherwise should I just burn holes with a hot poker?

I got my buckets from asda ...  scored round the pot 3" from the bottom ... then took a stanlye knife and cut through that way ... had my aubs pots in them ... worked a treat!

I grew some early pots in some of my freebies. We had them at Christmas time they tasted lovely maybe smaller than was expected but owt for nawt I say! I have also planted bare rooted fruit trees in them to limit the size until I can afford the root ball restricts. Carrots did well no carrot root fly, rasps, blackberries etc all started off in these free pots whilst I was sorted my  garden extension. Still not done 'cos of the big fella up there constantly showering over Hull! I will get there