I tried looking in Amazon, and they've got an assortment of hole punchers, mostly with a rotating head of 6 sizes of punchers. I question the sturdiness of these and really only need 1 size. As for the size of the holes I'm looking for, I tried measuring them with a ruler, and it looks like they're just a hair under 2 mm. If there is such a thing as a standard size strap hole, that's what I'm looking for. Amazon has something 1.5 mm, but I wonder if that's too small. Any recommendations? The straps I have are 3-4 mm thick. Cheap but sturdy would be nice. Thanks!