[antonye]

B&Q will sell you some mesh. You can pick up various mesh sizes (bigger/smaller holes) and in different finishes too. I would go for the anodised alu stuff (can get it in silver or gold) as it won't rust like the steel mesh does as that is untreated. I think mine was a fiver for an A4 sized sheet.

Halfords also sell mesh too. They sell it in much bigger sheets for the drainpipe-exhaust brigade! You might be able to find something suitable there if B&Q don't have what you need.