Good for you. Making your own Hammer stalls are good projects to learn hand sewing of leather. Just one caution that some of the modern tanning methods of leather may cause rust when the cover gets wet and allowed to dry on the frizzen. Not so much of a problem with Veg Tanned or Oil Tanned leathers, but it is still best to take a wet Hammer Stall off the Frizzen and allow it to dangle by the strap, until it dries and when you get back home from a rainy or snowy day.
I've always made mine out of veg tanned leather, but buckskin also works well, as the following quote demonstrates.
Captain Robert Stewart of the Virginia Regiment writing to George Washington in March 1761 wrote”¦
“”¦.. the Nature of the Service we are likely to be employ’d in, will in some measure dispense with bayonets, we can make Lock Covers of Cow Hides, and Hammer Slatts of Deer Skines &ca”
Gus