Hmm, I'm noticing one potential problem. At the moment the dimensions of the barricades are 40mm wide, 20mm deep and 23mm tall (with the centre gap being 17.5mm tall).
Printing and casting them as solid models might be a bit expensive. Hollowing them out might be an option, but if I'd print them using Shapeways' wax, the model might become too fragile. Need more info on their material before I can do that. But I've got a feeling I might end up going to a more high-end service for this.
Now the idea of 'hollowing out' the model left me thinking: I could design the barricade in such a way that it consists of 2-3 parts (front, back, maybe a separate top). If the parts are interchangeable, I'd have a very modular barricade kit.
Food for thought...