Why would you not just buy a good one off amazon lol? Heres the one i own and it works amazing, also lets you punch different sized holes and punches them super clean.
Professional Leather Hole Puncher – Leather Punch Tool for Belts, Watch Bands, Handbag Straps and More – Precision Multi-Size Fabric & Leather Hole Puncher for Crafts & Easy DIY Belt Holes https://www.amazon.com/dp/B00KY3WAK6/ref=cm_sw_r_cp_api_glt_i_H248TWCSAE6M3SEYTBN9?_encoding=UTF8&psc=1
Try one of these. A lot cheaper than a drill press to start.
I bought one recently and it works great. You may need to use a piece of scrap when punching through thinner leather, but it’s pretty quick and easy. I’ve done a couple projects with the 2mm hole.
Also, to do holes in the center of a piece, turn the size you want opposite the usual spot. Hammer the tool from above. Not recommended for everything, a set of actual punches would work better. But this is handy enough in a pinch.
Those look fantastic. I was in on the waxy kudu jodhpur and I needed additional holes in my straps as well. I ended going with a leather punch and it worked like a charm. PLEASE get advice from Lorenzo or someone more knowledgeable since you have shell. The leather punch worked great on the waxy kudu but shell is a whole different game.
Just FYI, you can get something like this to reduce the odds of stabbing your hand with a screwdriver!