For my first ever CNC machined part, I decided to do a machinists level. This is a small right angle square with bubble levels in either end of the square. Since I don't have a 3 axis CNC in my apartment, I made it at TechShop. If you want to know more about this wondrous place of making, check it out at www.techshop.ws.
Step 1: Create a CAD Drawing
The first thing is to draw the level in a CAD software package. I used AutoDesk Inventor at TechShop to draw the part. The basic dimensions were 2"x3"x0.75".
Step 2: Create a Tool Path
The next step is to create a tool path using CAM software. Since I only know Cut3D at this point, that is what I used.
Step 3: Machine the Blank
Take the tool path created in step 2 to your 3 axis CNC of choice, set up the block of material, and make chips!
Step 4: The Bubble Vial Holes
Get two bubble vials from a cheap level and measure their outer diameter. Select a drill bit close to, and maybe just a tiny bit larger than, that diameter. Using the CNC mill makes this process really easy - just find the edges of the ends of the final piece, divide the thickness by two, and pick an appropriate midway point on the width, and the machine will go right to it within a tiny fraction of an inch.
Step 5: Insert Vials and Seal
Once the holes are drilled to a usable depth (I had to repeat that a couple times because I eyeballed the depth and it wasn't deep enough to center the vials in the machined windows), insert the vials and seal the holes. Originally, I thought to tap the holes and use set screws to seal the ends, but I just used silicone instead.