Quote Originally Posted by tuggyne View Post
Assuming you're using [shadow] spells in 3.5, the bridge-type stuff works but the others do not; objects auto-succeed on their Will saves, so the pools of acid and ceilings will collapse right through the shadows most (all?) of the time.
I was assuming a fair amount of DM fiat for this to work. Basically making it a property of this specific demi-plane created with epic level magics that the powerful wizard had access to.

As for a specific spell to replicate this, the closest I can think of is a 2nd edition spell called "There/Not There". Maybe that can be ported over to suit the DM's purpose.