After doing some extensive testing of the tool length offset formula, I found it to be almost dead on every time with a consistent 0.0015" tolerance.
Next, I wanted to test tool collars and using different endmills. I went to my local ace hardware and found small plastic nuts (I couldn't use washers as they didn't have any that would sit tight enough) that I could use as tool collars. These nuts were just tight enough that you had to push down hard on the business end of the bit to get it to fit, which was good to prevent it from sliding around.
I measured each bit and inputted the information into my formula to find the tool offset. After doing that, I set each one as a different tool with a unique ID for each one (i.e., #1, #2, #3... etc.). I then went into fusion and created a series of facing operations with only one difference, the tool. I ran each one and had near dead-on accuracy with each tool almost touching the face. To be sure I wasn't just running too long of a tool first and all the other bits just running over a large void, I switched the order of the tools and had an identical result as before.
Now that I have tool collars on each of my endmills, I needed a way to organize them as they no longer fit in their cases. I went to fusion and spent about 13 minutes coming up with a simple design to display and keep them in proper order. I am only able to use 0.125" or 1/8" tools in the Pocket NC v1, so I did not need to make any smaller or larger sections. I did offset each hole by 0.15" to make sure they would fit.
I then sent my design off to the 3D printer with a 40% infill and 0.5mm wall thickness for a total print time of 1 hour and 52 minutes. It turned out nice, and each hole gave the bits a snug fit. I only have like five tools I will actively use for the Pocket NC, so I only made seven slots.