I made a bigger jig like this years ago, out of thick plastruct plastic sheets, and used chicago screws as the pivot points. To make it a little more versatile, I sized the centering holes the same size as the other holes, and with a couple more screws that allowed me to add a third arm in the center which can be exchanged for different needs, exactly the same length as the ones at the edge. Need extra small belt holes? Make a center arm with small holes that fit that small punch. Need an oblong for the buckle tongue? Make a center arm, use that oblong to punch the plastic the right size and orientation and your oblong is centered and as straight as you were able to make get the plastic.
You can also make a couple of holes in the edge arms and add a stiff wire pointer to set up hole spacing to help you move the jig the right distance for even holes.
I took the idea so far as to put the design into cad software with a measurement scale on the arms to assist with spacing, and some accessories with the intent of having it laser cut in some nice clear plastic! Unfortunately, before the laser cut folks could get to my project, they went out of business. So, for now - my old jig still works even if it doesn't have all the niceties.
- Bill