This small thin piece was easy to cut and it went quickly compared to the larger/thicker ones. 
 

I'm going to use some 3/16" mild steel round bar to make some pins, which will be inserted into the five inch round pieces. You'll get the idea soon...
 

I used my metal cutting saw to cut the pins with but quickly found out the blade that came with it wasn't ideal for this smaller diameter material. My blade doesn't have the tooth count that is really needed for this smaller material because it was bending it as I cut though.
 

I ended up putting a thick piece of steel behind the bar stock right next to the blade (not shown). This remedied the problem but I really need to buy a blade that has a large amount of teeth to cut something thin like this again. Note the blue bucket: I put a plastic guard with a mag-base covered with a rag to help catch the pieces as the flew off. But it only caught about 50% of my pieces.
 

Here is another simple fixture that I used to put in the holes for the pins. I'm using a 3/16" diameter end mill in place of a drill for this operation.
 

My digital read out has some nice features, including one for bolt circles. All you do is input some parameters, like the radius of the bolt cycle, how many holes, starting point, etc. and then hit go. The next screen that appears has the X and Y coordinates that you need to dial to.
 

Once you have your numbers read zero, you're ready to work on that hole (drill, ream, using and end mill, etc.). When you're finished with that hole location, you hit "Next Hole" and it gives you a new set of numbers that you move to. You keep doing this until you have all your holes done, then replace your work piece and repeat the process again. Very simple.