Huh, now I'm curious, what did the D2 look like?

Lenticoidal, I guess? I.e. remove the outer face of the cilinder by making the faces curved

Yeah, that was my thought as well, but that's also basically a D3 with a really small third edge, in practice. I was wondering whether there's some clever shape that actually is a D2, though maybe that's a Möbius strip in reality.

> with a really small third edge

Doesn't every die have a bunch of edges or even vertices that aren't considered faces despite having a measurable width? As long as it's realistically impossible to land on that edge, I think it shouldn't count as a face.

> what did the D2 look like

> though maybe that's a Möbius strip in reality.

You're close, it looks like a failed attempt at doing a möbius ring.

https://www.awesomedice.com/products/the-d1