There are production methods of doing some things so that you can make parts faster. One way is to use a larger endmill to hog away areas before you go on to a finish endmill for the fine detail. If you are going to make a lot of keychains (a lot to me is more than five) there are other ways to boost production.

When cutting with your 1/4" endmill to remove the bulk of the material, you could also drill a hole at a set location on the blank. I noticed you have a strip of raw stock. The hole would be your fixturing key for doing a number of medallions on a blank. After the bulk is removed and you go to the 1/8" endmill, you set up a stop with a 1/4" dowel or screw to fit in the 1/4" hole the larger endmill made.

Place the stock over the dowel and tighten the vice. You should now have your roughed in blank close enough that the finish amount will all be cleared by the 1/8" endmill.

The big thing is using a larger endmill to remove the bulk of the stock at a much faster rate. Even for one part, the extra time doing the CAM portion is minor compared to the savings in time for stock removal. Plus a larger endmill is more robust and less prone to breaking while doing the tedious work.