You're off to a decent start on leather working.
If you can do a three-part flat braid, try your hand at a four-part round braid, and end with a turk's head knot. You can find instructions online, although I recommend buying a book on braiding and lacing. If you can get comfortable with that, it makes an excellent decoration for all kinds of stuff (including sporrans). You can impress friends and neighbors and people at parties too!
As for the antler sheds, You can make leather working tools out of them. For example, keep about a 6" length of antler for rounding leather edges. Sometimes you'll want to create a nice smooth edge to the leather using a beveling tool, but even after you bevel it you'll want to smooth it down by rubbing something smooth over it. An antler makes a great (and cheap) tool for that.