Mostly for cutting and laying out stitch lines and keeping them straight in fairly stiff leather. I know at some point I'll want to make a decent knife sheath and a ball bag etc. I could buy the ball bag but what's the fun in that? The knife I want the sheath for is homemade with an 11 inch blade and a big chunk of elk antler for a handle. I can't buy that unless I have it custom made.
A good knife. One of the smaller round knives would probably do you well. Maybe with a 3-1/2" blade. Get a good quality one or make your own like I did. H.G. Gomph, vintage C.S. Osborne can be found on ebay almost all the time. Check with
Bruce Johnson. He lists lots of good older tools. He's a leather worker himself so you can call and talk with him about your needs, too. Some guys use a box knife but I find I do better, and safer, work with a blade that cuts away from me rather than one you drag toward you.
A stitch groover. One of the better ones I've found is
the one in the photo.
A pair of dividers will let you mark any size stitch.
A stitch awl. I like the
Vergez-Blanchard ones but there are a lot of good ones out there. My favorite is one of the 38mm ones.
A small to medium edge beveler for most holster sized projects. I like
these. You can get a full set of blades but the "1" will do most holster sized work.
A straight edge. I prefer an 8" x 12" carpenter's square for most smaller projects but there are times you need a longer one.
To stitch, you'll need some harness needles, thread and bees wax.
Oh, yeah, everything needs to be sharp. S H A R P! I strop my blades on a piece of leather with jeweler's rouge on it. When the blade starts to drag on the leather, strop. That is true for your stitch awl, too. Sharpen everything and keep them sharp.