Today I got fitted for removeable dental fill-ins/what have you. It was a fairly simple process, but a weird one. First the dentist's assistant put a couple of things that looked like U-shaped sink-strainers in my mouth to see if they'd fit over the teeth. Then the dentist herself came in and made notches on the enamel of the teeth that will be neighboring the dentures. Not really painful, but still, it is a drill. Then the assistant filled in the sink strainers with this algae-derived... stuff. It's like rubber that's somehow in semi-liquid state at less than room temperatures. But somehow that hardened enough to take impressions of the teeth, and she removed it. There were still some eraser shavings left behind, or what felt and tasted like bits of eraser.
Not bad overall. Did not involve the taste of blood, anyway.