This is a technique in which guests can walk through any wall by building a path through it, regardless of it's default clearance:

- build a wall
- Use the zero all clearances option
- build a path through the wall
- restore clearances
- done!

Guests will walk right through the wall/door afterwards. There are virtually NO graphical glitches either. You won't see doors "open" when they walk through though.

Cool nice effect. That is nice! B)