This application is primarily for developers who need to emulate a different build config environment from a given device. (This allows you to work with certain android.os.Build fields that only exist on certain devices.)
It will generate two files in the root of /sdcard/
android$os$Build.smali
and
android$os$Build.VERSION.smali

These can be dropped into the root of your smali code and then you can replace all desired references to Landroid.os.Build; with Landroid$os$Build;