Sharing a project and custom domains
Sharing is a switch in the project's settings. On, the project is public at <code>.runsnip.net; off, that address stops answering. The shared page is the project as it is saved now, built on the server, with its source not served.
A custom address (<name>.runsnip.net) and a password can be set in the same place, where the plan includes them.
A domain of your own: point it at <code>.sniprender.com with a CNAME record — or, at the top of a domain where a CNAME is not allowed, add a TXT record at _runsnip.<domain> holding the project's code. The domain answers once the record has been seen; the project's settings say whether it has.
How many projects can be shared at once depends on the plan.