How do I turn a leather belt into shoulder strap for a purse?

Rivets

Hot glue would work, or you could ask at a store like Michaels or JoAnn if they could suggest a better glue.

Look at this site: https://www.pursesupplydepot.com/default.aspx it’s called Purse Supply Depot. You can find the hardwear here to help you turn your belt into a strap. You could use the buckle as a cute design element but you’ll probably need to hand stitch the opposite end, unless you can figure out another way to secure the strap at the other side. It’s hard to help more without seeing your purse to know what you need. You may want to look up Crafty Gemini on YouTube she makes allot of bags so you can see how straps are done but she does use a sewing machine. You’ll need a leather needle and a thimble to hand sew unless you find an alternative but I think you need to hand sew I don’t think adheasives or fuseables alone would be strong enough, but I would use an adheasive then handsew for extra security.

http://zakkalife.blogspot.com/2011/08/how-to-make-shoulder-strap-out-of-belt.html?m=1

https://www.instructables.com/lesson/Creating-Leather-Straps-and-Handles/