The included 3MF file is sliced for the X1C, this can be changed to the other Bambu printers in the slicer. It has a layer height mod, so for this to work properly you can scale the bookmark on the X and Y axis but leave the Z height where it is currently at.

0 bottom and top layers, the layer height mod creates a solid layer over the face of the moon (the bottom is still infill).

Choose your infill, but make sure that it is compatible to be printed (octogram spiral is an example of one not compatible).

5-8 walls recommended for a sturdy bookmark.