I mentioned this in my other comment, but the hobby is basically three parts -- big DIY, small electronics, and software/sequencing. Some people really like one or two parts of it. Some people will buy kits and spend all their time making sequences.
Some will spend all their time building and then buying sequences.
I personally end up buying sequences because I run out of time. I've made them before, but they take about 50 hours to make one song. I sadly don't have that kind of time, so I spend all my time making and then shortcut the end so that all the making serves a purpose.
Vendors sell the sequences for a song, and they typically have certain events plotted out. You then just take the timeline in the sequence file you purchased, and map your props to parts of it
It's somewhat akin to taking a midi file and setting various instruments to the various channels in the file
Some will spend all their time building and then buying sequences.
I personally end up buying sequences because I run out of time. I've made them before, but they take about 50 hours to make one song. I sadly don't have that kind of time, so I spend all my time making and then shortcut the end so that all the making serves a purpose.