We often play GWs "The Hobbit - Escape from Goblin Town". The set comes with a few plastic platforms but these were quite limiting after a while. So I started making more and different terrain pieces out of scrap polystyrene packaging, cocktail sticks, coffee stirrers and any other bits I could find.
The terrain pieces will be used in other games too.
The well - where the goblins come up
The watch tower - I wanted a rickety looking structure and achieved
it. then discovered that it fell over so had to extend the
structure for balance!
The jail, cage etc (with opening door)