Huh? I’ve always used a 3mm drill for a hole for M3 bolts, 4mm drill for a hole for M4 etc.

If you want a bolt to stick in a hole, you’d need to make it threaded using a tap. These holes need to be drilled even smaller (and there are charts for that), and the material would also need to be sufficiently thick or the thread will risk ripping.

I’d suggest that you instead use either threaded spacers with bolts from the top and bottom, or “barrel T nuts” if you can find them in a size that would work. There are also “Chicago screws” but they are really for leather-making so they are often not always made with as high tolerances as machine bolts.

I get only an empty page when I click the Nickel link.