this is a nearly minimalistic bookmark.

just a .2 mm plane with a little stopper at the end (1 by 1 mm) and a loop for connecting a string put 4 or 5 on the edges and you have a bedleveling test (and some bookmarks if level is OK)

my wife loves it, because it holds well, doesn't stick out much an she can use many different colors in one book to find different topics

ps: it takes much longer to heat the printer than to print it :)