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These pieces were done on a 60 Watt Epilog, and I have since done some on a 90w Full Spectrum. settings are going to be pretty different on a lower power laser, but I am sure it can be done. If possible, try to make a single pass. I would start with maximum power and lower the speed until you get acceptable results. Leather will shrink when exposed to heat and if it gets or stays too hot it can warp badly.If you must make multiple passes to cut through, try using some strong magnets to hold the leather down against the bed and prevent it from moving between passes.
Looks great. I found the pattern would not work for a XD, but I bet you can tweak it a little, to make it fit just about anything.
This all depends on the kind of dye you choose, and whether you seal the leather after dying. I get good results from Tandy's leather dying products and also from common wood stains (e.g. MinWax) from the hardware store. Anything that is going to be worn against clothing may bleed when it gets wet or sweaty if it isn't sealed, so I always seal (at minimum the outside of the leather but usually all exposed surfaces) with a product like Tandy's Eco-Flo Satin Shene (sic) or Super Shene. This will give the finished piece a controlled level of shine and prevent the dye from bleeding.