Here's a nifty prototype for a pen whose cap you'll never lose:
That's by industrial designer and professor Tomas Kral. In addition to teaching ID at Switzerland's ECAL (Ecole Cantonale d'Art de Lausanne) for the past 15 years, Kral runs his own product design studio.
Looking through his book, I spotted this design for a very different object with a similar mechanism to the pen:
That line of storage containers is amusingly named for their inspiration, Clown Nose.
Kral's book is pretty deep, and well worth a look. Check it out here, or see his Instagram.