What do the walls of am finite demi-plane look like?

[billd91]

I'm most inclined to do the old screen wrap like many old console games like Atari, you just come back in on the other side. It becomes kind of like circumnavigating a globe.

Alternatively, I could also picture a demi-plane as an enormous castle with no exits. I think it would otherwise be possible to construct an environment for a plane that just has no exits, no open place to roam, and so no perception that they are, in fact, reaching a border.