I agree with most of this comment except for the hardwood boards being overkill. If this pantry is going to endure for decades, it's worth using hardwood just to reduce the dents and shallow gouges that come from regular use.

Maple is about 3x harder than pine, and it will look considerably better after a decade of use than a bunch of 1 by from Home Depot.

Use step drills on sheet metal too. There's no upward force component to pull it out of the clamps or vise.