This is something I've been working on for years. I'm clearly inspired by the TOS insignia for the crew of the Enterprise. I've been playing around with shapes (quite literally for years now) trying to pin down something that I'm pleased with.
I was monkeying around with a similar idea a while back, towards incorporating the insignia into the design of a spacecraft. Here's what I did:
I think I'm leaning towards using shading to suggest a beveling, to complete the underside curve.