BrewLAN is a unitpack and balance mod created for Supreme Commander: Forged Alliance with various unit additions and changes at all tech levels. All of the units are crafted to match the styles of original units and to bring balance to the madness, as opposed to being overpowered and making all other units redundant.
One of my current projects is allowing the Gantry to build experimental units from other mods properly. The script that allows this can only do it on a unit by unit basis at the moment, and also disables the unit from being built by anything else, but here is one of the first things I tested; the Doomsday from the Total Mayhem mod. Which takes the Gantry just under 10 minutes at 764 mass per second to build.