Not quite sintered armorgel but...
Behold the Ribcap, a hat or helmet-liner made with something called d3o, a responsive material which is flexible normally but goes rigid and energy-absorbing on impact (website - wikipedia). This is a goofy tank helmet liner one from Streetgadgets which made me think of Tank Could it mean the death of the bike helmet as oldschool cotton caps get techno? I'd love to think so.