Here's an idea for a gamemode I had earlier, dunno how feasible it is though.
 - Each team gets an AI player that has no units (does that even work? maybe they can have an llt or a duck).
 - You start with commander and coupon as usual.
 - Any time you build a unit, that unit is immediately given to the AI on your team.
 - All builders except com and facs are disabled (sorry funnel, athena).
Thus, you build stuff. AI fights with the stuff you build.