This is something I found on thingiverse, cut from 1/32" birch plywood. Surprisingly the speed and power to cut this was the same as my 1/8" stuff, must be some dense stuff.
This will be going to one of our librarians at work, will see how long it takes her to notice it.
I found the plywood to be a bit stiff and could possible tear the pages of a book if used with the lip that was cut into them. I have a bunch of business card sized cardboard/kraft paper cards I got. I found I could stack these and cut 3 of the bookmarks out at a time.
I took a few to work and placed them around my co-workers desk. She went almost all day without noticing, so I finally walked up and pointed one out. She about fell on the floor laughing, but they fit in with her personality so well she didn't notice the one right in front of her staring her in the face.
They seemed to be a hit, I gave all of them away, so came home and cut about 40 more out (15 minutes worth).
Yeah, been thinking about doing that one as well, others have mentioned that was the first thing they saw when they looked at the large smile shape in the middle.