When finishing the edges of a piece for a more professional / less rugged look, there are two primary methods. One method is a process of burnishing, dyeing, and sealing. This method works great for some leathers, but does not usually work well with others; chrome tanned leathers in particular. When finishing these edges, or when a more European finish look is desired, the preferred technique is to use an acrylic edge paint. Here I will outline the process for this method. It is not quick or easy, but it is one of those things that can really set your piece apart from the competition.
1) Make sure your leather is aligned well. You don't want one side of the edge to hang over the other. One way to do this is to wait to cut one side of the leather until it is attached to the first.
2) Sand the edges with a high grit such as 600-800. We need the edges to be porous for the paint to adhere well. If your edge is too smooth, the paint may not adhere well and can peel off.
3) Apply paint. This base coat should be a rather thin layer if you are going to use step 4.
4) Seal paint (optional). For the first layer of paint, it is a good idea to heat the paint and melt it into the leather to get the best adhesion. You can do this by burnishing, or with a heated iron*.
5) Apply paint. Apply a generous layer to build up your edge.
6) Sand edges to sculpt the shape you are going for, and to improve adhesion for the next layer.
7) Repeat steps 5 and 6 until you have the coverage and shape you desire
8) Burnish with wax. Rub the edge with parafin or a beeswax/parafin mix. Take a canvas cloth and rub the edge quickly to melt the wax along the edge. This provides a nice polished / finished look.
* If you have a edge heating iron, you can use this after each layer of paint has dried, in order to even it out and make corrections. Do not use a regular soldering iron unless you have it operating on a dimmer switch, as they are too hot and will melt the paint too quickly, and can even burn it.