I designed 3 different stamp patterns for this experiment:

-A geometric stamp that I thought would look good stamped in a grid

-A stamp loosely based on a circuit board for more random pattern creation

-A faceted stamp that would create a simple interesting texture

I created the first two by finding images I liked, importing them into Fusion as canvases and sketching over them. I then extruded these sketches to a height of about 2-3mm and added details. In my first iteration, I left the top surfaces of the stamps fairly flat, but I found that chamfering the edges so they came to more of a point at the top helped the pattern have better definition when stamped.

I created the faceted stamp by making simple pyramid shapes in Fusion and putting them together. My first version of this stamp had too much relief, so that when it was stamped, only the very tips of the pyramids made imprints in the leather. I fixed this by playing with the scale in the Z axis.

By varying the depth of features in your stamps, you can create some difference in line weight, relief and shading, but this will only work within a very small range of about 2mm or less.

I also kept my stamps between about 2 and 3 centimeters across and printed some in different scales to see what looked good. I think you could potentially go bigger, but eventually you won't be able to exert enough pressure with a hammer to make a good impression with a large stamp.

To finish my stamps, I gave them each a solid base about 5mm thick. I cropped the profile of the bases roughly around the shape of my designs to make it easy to see when you are stamping and line up your stamps. I also cut out a socket on the underside of each stamp. I made this socket the diameter of my aluminum rods and about 2mm deep. This will help hold the rods in place on the stamps.