As of now I have only done the first 5 puzzles a few days ago.
I wish that the warning of using my own pieces had been given in a more obvious and eye-catching way before I printed and made the figurines, perhaps the same page as the cutouts or at the very front. The cutouts are very fiddly and I definitely spent more time making the pieces than completing the few puzzles I've tried.
Otherwise, it feels strange to be given a par on each puzzle with no example of how to record my moves until I thought to check the back for if/how solutions were given.