It was very time consuming! The key tuning process alone took most of the half year, and I screwed about quite a few keys over the course of the project - The nice thing though was that it broke the large, intimidating project into very manageable chunks. One key would take anywhere from 30m to 2h depending on the size of the key and my own skill as it developed throughout the process, so I could generally bust one out in the evening, or half a dozen over a weekend. It was very satisfying to watch my pile of keys grow!

I wrote down some basics of the process here

https://lemmy.ml/comment/495852