WhatsApp Kiss
thingiverse
Just for kicks, let's give it a try. A 0.25 millimeter space is what you'll need to start with. The heart shouldn't have any room for error, so some extra adhesive will be required. (I have no connection whatsoever to WhatsApp.)
Download Model from thingiverse
With this file you will be able to print WhatsApp Kiss with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on WhatsApp Kiss.