A CNC cut branding iron just doesn't have the feel of a handmade one. It's not so hard to make one yourself.
I am going to show you how to make a heated branding iron using 1018 steel. 1018 steel is a mild steel that is ~0.18% carbon, it works easily but not too soft that it becomes difficult to achieve a clean edge.
If you want to strike your brand into something I suggest using 1075 or 1095 steel, these are stronger (harder) than the 1018 steel.
Brass or bronze or copper can also be use, but these are going to be softer than the 1018 steel. The video provides extra details and what my brand looks like on a variety of material.
Step 1: Design
The design on a brand needs to be reversed from your intended design. A simple way is to trace the outline of the design on a window. Glue the design onto a piece of masking tape and trim it up.
Step 2: Preparing the Steel
If you chose a round bar then I'd advise grinding two parallel sides on the round stock. Then cut it to the proper length, ~0.5 to 1". The parallel sides is going to help the stock to be griped in any vise.
Step 3: Transfering the Design
I am using 1018 steel, so I can trace the outline with an exacto knife whose blade is usually 440 stainless steel. 440 is harder than 1018. I then used an electric engraver to put little holes around the design so when I drill the negative space my drill bit will stay put. The red in the photo is the negative space.
Note: if you use a harder steel you may not be able to transfer the design using an exacto knife.
Step 4: Rough Out the Design and Test Burn
Remove as much of the negative space as possible with a drill press, use WD40 or similar as a lubricant for the drill. The drill only needs to go down ~1/8" deep. Use a cutting wheel dremel attachment to clear rough out the design.
Do a test burn. I heated the brand on a electric range top. See video for details.
Step 5: Fine Finishing
Use diamond coated dremel burrs (and WD40) to clean up the design. I suggest carbide tipped burrs as well. Finally, use a file to flatten out the top. See the results of my brand in the video.