I wrote an article on my web site presenting three kinds of edge burnishers for lather working.
La Belle Note - Edge burnishers
Here is the first, a manual one :
This tool is most often made of beech, but one can also use a naturally siliceous wood such as iroko for example, which will give it a slightly abrasive power and which will heat a little more efficiently.
All parts of the tool can be used. The curved head for crushing pieces in full leather for example, the three grooves of three different thicknesses for the edges, and the conical part for flat or closed parts.