Originally Posted by
awerby
It looks like what you want to make are coining dies, not what I thought of as "stamps". An etching process isn't going to give you those contoured surfaces; it works on one level at a time, like 2.5D machining. I'm skeptical of the ability of a cheap router to do a good job at that, but it's true that when you're using very small cutters on steel, you don't need as much torque and you do need a lot of speed, so a router-type spindle can work. If this is all you want to do, I'd suggest you look for an older pantograph machine. There are a lot of them coming onto the market as the industry upgrades to CNC machinery and a digital workflow. You'd typically make the pattern much larger in plaster or a similar material, and then use the stylus on the pantograph to trace over the pattern while the mechanical linkage reduces the movements to the size of your die.
Of course, you can do all this digitally, either using a 3D scanner to capture the pattern or modeling it directly in a CAD program, then using a CAM program to translate that into tool paths a CNC machine can execute, but it sounds like you aren't really going into heavy production on these things, and you'll need to save up for a coining press, or make one that drops a heavy hammer head on your die from a height.