Researchers say we don’t put on enough sunscreen. A Seattle startup has come up with a potential fix: an invisible ink stamp that notifies you when it’s time to re-apply. Michael Croix ...

What makes a good 3D-printed stamp? It should be easy to use, transfer an image cleanly, and retain ink reasonably well. To hit these bases, printing the stamp face out of a flexible material is ...

The ink will only stick to the raised areas, of course. Natalie Wallington 9. Test your stamp. It’s time to give your stamp a trial run. Brush away all excess rubber crumbs and pat ink onto the ...