Coffee mugs and cups have been used popularly to hold napkins in México.  Napkins are rolled up and placed inside the cup.

These 3D printed napkin holders take the mug-as-a-napkin-holder concept further by changing completely its purpose into a functional, funny and stylish napkin holder that can only hold napkins.  No liquids allowed, hot or cold.

Coffee mug napkin holders white smokeCoffe mug napkin holder black