I’ve been wanting to try out metal cutting for a while, but it’s pretty intimidating — a lot less forgiving than what I’ve tried before (wood, foam board, and plastic).
I decided to start out by carving some coins. At first I wasn’t sure if it was legal, but as far as I can tell, it’s only illegal to modify US coins to look like other currency — turning them into non-currency is fine.
I’m using nickels, because they’re thicker than any other common us coin. I took inspiration from this post for a coin vise: Work Holding Solutions: The Soft Vise for Engraving.
I modeled the vise in Fusion 360, with the diameter of the coin area slightly smaller than a nickel. That way I could use a flathead screwdriver to wedge open the gap, place the nickel in, and have it firmly stuck in there.
After a few prints to dial in the dimensions, I mounted it to the hybrid table on my Shapeoko Pro.
For this proof of concept, I wanted a simple design, and Halloween_JackOLanterns_1 from Design Elements was perfect. I used the default feeds and speeds for Aluminum in Carbide Create to face and pocket the design.
I screwed up the zeroing on the first try, but the second try went really well 
With that success under my belt, I wanted to try something more complicated. I moved over to Fusion 360, and pulled the center design out of Celtic_Shield_2 in Design elements. I started by pocketing the flat areas with the 1/16" flat end mill I used on the first design, then moved to a 1/32" ball end mill for the details. The simulations were looking great:
However, in trying to dial in the feeds and speeds in Fusion, I actually broke both of the 1/16" end mills I had, so that design is going to have to wait until I can get new ones delivered 
