Stronghold Assault includes an entry for a Void Shield Generator, the rules for it are pretty cool although a bit vague in places and if interpreted literally (as many do) a bit silly. No model exists for the entry which is described as an impassable building with battlements, so how big is it? My friendly local T.O. posted up some specific rules on his blog here. I had already built one model for a shield generator, but I decided to build another according to his specs.
Here's my original model in a WIP state:
And the new one
The structure is cut from foam core board, covered with plastic sheet from a 'For Sale' sign purchased a the hardware store, The 'plasma coils' are pieces of flexible conduit cut to length, then split lengthwise.
For those who are interested, here are the templates I built the second one to.