Jim Reed wrote:
I am in the midst of fixing some farm machinery with new sheetmetal. The
metal I am using is 14 gauge, and the proximity to moving parts requires
carriage head bolts. The previous metal used 1/4" carriage head bolts, and
I would like to do the same. I don't have any idea how to create the square
holes. Each piece of metal is roughly 3 feet by 2 feet, and the holes will
be within 2 inches of one side of the metal.

Any help would be appreciated.

These would have been punched originally. It is certainly possible to get one of
those Whitney hand punches about the size of bolt cutters, and order a 1/4"
square punch and die set from Cleveland Steel Tool or the like.

I'd punch the holes anyway (drilling sheet is a real bummer) even if you only
have a round punch, punch 'em a little big and just pull the bolts through.

GWE