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.
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Step 1:
create sheet and punch one hole in a corner and press rectangular.
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Step 2:
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 -
Step 3:
end result