I made a wallet from shell cordovan and it is amazing. Holding up well after a year and developing some great character.
If you are skilled enough to do the leather justice, I say hand sew it. Same with cutting by hand. If you can't do it well enough the first time to satisfy yourself then it'll get awfully expensive. I think with labor and materials I probably have about $120 into mine, not counting the process of making wallets that led up to the one I made out of shell.
As far as working with shell, its a damn dream. It is nice and firm but still pliable, smells amazing, and will burnish with hardly any effort. I'd recommend watching Little King Goods' video on YouTube where he makes a wallet out of shell just so you can see it before you do it. The stuff is almost magic but it is soooo expensive.
Please keep us updated. It is a lovely material.