I have a 3/8 inch hole punch; it looks like this:

I want to use the punch to make holes in business cards; there are two problems with this setup as-is:

1. There’s no way to ensure that the holes I punch are centred horizontally on the cards.
2. There’s no way to control the vertical distance from the top of the cards that the hole gets punched, other than pushing the card all the way into the punch.

I want my holes to be centred and about 1/8 inch from the top of the cards, but because of these limitations, the best I can do is eyeball the horizontal centre and get holes about 1/2 inch from the top, like this:

Clearly what I need is a “jig,” a device to wrap around the hole punch to solve both problems.

To the 3D printer!

I designed a jig in Tinkercad with a slot for the hole punch and guides for a business card:

The design took just over 2 hours to print on my Monoprice Select Mini 3D printer:

With the hole punch inserted, and a business card ready to punch, it looks like this:

And it works!

Here’s a perfectly-punched hole:

Now I’m off to punch lots of perfect holes in lots of cards for a New Years card project I’m working on.