The main step between the holes is 6 mm (around the zipper 5 mm)
Thread thickness 0.8 mm
Used vegetable tanning leather 2 mm and 1.6 mm (thickness marked on each detail)
Solid Brass Slide(32mm):https://s.click.aliexpress.com/e/_99ZGyo
Solid Brass Buckle(25 mm): https://s.click.aliexpress.com/e/_AsiQDE
Hole Punch: https://s.click.aliexpress.com/e/_AB2XjK
Hole Punch round: https://s.click.aliexpress.com/e/_AYqhVI
Pattern:https://www.etsy.com/listing/1044549480/leather-sling-bag-patternpdf?ref=shop_home_active_1
And for VIP members:
https://www.youtube.com/channel/UCMj-IxlbtBg7wAZGZPh-BYg/join