Semi-related:
Milkshape, or any modelling program which doesn't support quads, is probably not the best tool for making bricks, because .blb bricks are made up from quads. This makes the bricks horribly inefficient as the blb converter tries to make quads from the triangles, which not only doubles the face count, but also adds loads of unneeded vertices.
To illustrate my point, let's imagine a cube. A cube has six sides. If you use quads - a face defined by four vertices - you will only need six of them. If you are using triangles, you will need twice as many (twelve to be exact).
ON: Interesting idea, are these hand-made? If yes, did you take measurements, or did you simply eyeball the whole thing?