How to create a perforated sheet metal
could be that you want to use rectangular patern. by creating one hole and copying it over the surface of the sheet. i actually never use sheet metal parts but here it goes.
create sheet and punch one hole in a corner and press rectangular.
as feature select your hole. direction 1 the long side of the sheet
direction 2 the other side. fill in the required amount of holes per side and spacing and voila done