I've made this warband/roster sheet for GDFF. It's not a proper army builder - just a roster sheet. You still need to reference the units from the army book and add up the values manually.
It follows the philosophy of GW's Kill Team, as that's the way I play GDFF at home: you create a roster of up to 20 units, which can exceed the points agreed for a game. When playing the game you select the units from that roster up to the points agreed for the game. The sheet allows you to create various "configurations" of your roster, this is, prebuilt sets of units picked from roster up to the game points.