I got tired of making a new cardstock template every time I wanted my sewing holes positioned slightly differently, however, none of the templates with regularly-spaced holes offered enough flexibility for my preferences. Enter: the adjustable punching template! 

This template, designed to be used with a punching cradle, allows you to slide sets of paired holes (designed for sewing around half-inch tapes) to whatever position you would like, with moveable single holes you can place at the head and tail. If you don't use tapes in your binding, you can print more of the single-hole sliders instead.

The main template is available with an imperial (8.5") or metric (210mm) ruler, and the holes come in two sizes (for punching with a needle awl or with a larger awl). The ruler is positioned diagonally so it IS printable on the A1 mini!

Please note that this model is only the template, not the cradle. You can find punching cradle models here on makerworld, or make one out of other materials--I'm still using my trusty old foamcore punching cradle that I made years ago when I started bookbinding.

I made the paired holes to fit around half-inch tapes because that's the size I use in my binding, but if people are interested in different spacings, let me know in the comments, and I could make others.

How to assemble:

First, partially insert the screws into the sliders, until the threads are no longer visible. 

Next, carefully insert them into the ruler. The flat center part of the ruler should fit between the slider and the head of the screw. 

You can hold the sliders by the screws to slide them along the length of the ruler. If it seems too stiff, run it up and down the full length of the ruler a few times to loosen it up. To anchor the sliders in the position you want, simply tighten the screws.

Once you have the pieces set up the way you want, place the template in the fold of your book pages in a punching cradle, and punch!