After learning how to use a manual mill, the first thing I did was run to the cutoffs bin and pull out a chunk of aluminum. As it turns out, this would be how I learned about different alloys and grades of metals. This aluminum ended up forcing me to learn the difference between 6061 and 6063, and how to use a horizontal bandsaw. I then squared the stock on the mill and used a center drill to make the numbers. My first time using a DRO didn't turn out too bad! The last steps were to fil off the sharp edges by hand and polish the faces. 

Stone can't be "machined" traditionally. To make anything of it, you have to grind it away, not cut. In contrast to the precision of a piece machined using a mounted tool with a DRO, this had pretty much no specific tolerances in flatness, smoothness, perpendicularity, or even standard dimensions. That's because I cut the stock material out of some old countertop material, using my mother's tile saw, which I outfitted with a grinding blade I found in the garage. Then I spent the better half of a day sanding the faces flat and somewhat square by hand, measuring only by eye. The fillets and numbers were made using a grinding bit on my Dremel tool. I have a new appreciation for heavy precision manufacturing.

I firmly believe that CNC machining is the next best step for any engineer involved with mechanical systems. Historically, the job of the designer was the engineer, and a trade machinist would operate the manufacturing equipment, because learning to work manually with metals can take many many years. In the 21st century, any college freshman can learn at least basic CNC milling, which is exactly what I did my first semester. I read articles and watched videos about speeds and feeds, fixturing, CAM programs, and other aspects of the process. I ended up using a laser cutter to make jigs to hold my brass stock in place, and the evidence of my inexperience shows, if you care to look for the imperfections in the finished product. Nonetheless, this was an important kickstarter project for me, and I'm proud of what I learned.