The challenge took me a few weeks to make because "calibrating" a disk (determining the geometry of the pregroove) is incredibly sensitive.
After the CTF I tried really hard to make a repeatable calibration process with the intent of building something releasable. I even ended up measuring the details on every CD-RW and CD-R I could buy on Amazon.
But despite trying very hard, I never did make calibration patterns that were reliable enough that I felt like other people would be willing to go through the process.
It seems someone else has succeeded where I failed. Great to see!