Thanks for the suggestions but I think I've confused matters by mentioning the layout thing. Persist isn't what I'm looking for either.
I'd like to design a bunch of prefab traps, and then create them later with events.
So instead of creating a sprite object in game, I'd like to be able to create a group of sprites.
The traps are going to be simple things, like a group of different spikes with some walls, or a big hole in the ground with a jumping enemy. There'll be lots of them so creating each individual part isn't going to be the most efficient way I'm sure.
Think Crash Bandicoot but the obstacles are being generated randomly in realtime.
Hope that clears things up.