I designed this for my wife. Her previous bookmark has fallen apart as it was designed poorly. 

As I come from industrial experience, I decided to quickly design one that would be more durable but still thin. 

If you want the mouth printed to be more pronounced try changing the setting for the nozzle width to really thin like 0.12 instead of 0.4 

I propose that this is printed with TPU, but I currently do not have any. So I sliced this for PLA

It is up to you, but I suggest you use Yellow White and Black in that order while printing. 

If you like any of my designs feel free to donate, even one penny helps : )

Thanks !