Super basic bookmark that you can change the top and bottom surface patterns in your slicer. Personally I use Orca slicer and I love the look of “Octagram Spiral” pattern but you can see “Archimedean Chords”  in one of the bookmarks I made too.. In one of the photos you will see a phone case this is just to show the pattern with a tri color filament..

 I do not own the phone case STL but got it on here phone case for pixel 7

I Made all mine with PLA, dual tone for teal bookmarks and tri (RYB) for phone case. I personally like 155mm X, 50mm Y, 1.50mm Z, but change it how you would like.. 3mf will have my settings but the STL should be very customizable, just within your slicer.