I use SCons as the build tool. I tried several tools, and chose it since it is Python-based (and since it has many other features, obviously). Indeed, I need some computations during the build process, since it is parametrical; for example, the final dimension of the images is customizable. Therefore, I have automatized every aspect of the build process through SCons, so that cost doesn’t weigh on the development effort. Furthermore, the automatized build process allows us to implement Continuous Integration.