Future and his daughter weren't about to take their masks off at the BET Awards 'cause they cost a damn fortune to make.

You might have noticed Future and his little girl, Londyn, rocking Bane-like masks Sunday on the red carpet, and even during the rapper's performance at the show. Well, the hardware didn't come cheap ... try about $9,000 for 3 of 'em.

Sources with direct knowledge tell us Future's camp hired designers Marianna Harutunian and Xtina Milani to create 3 unique masks for Future and Londyn.

We're told Future dropped between $2,500 to $3,000 per mask -- all of which were made with brass frames and Swarovski crystals. Londyn rocked rose gold brass with gold crystals. Future had one for arrivals and another for his performance ... both with clear, black and orange crystals.

They took about a week and a half to make. Clearly, Future's was designed so he could rap through it.

MASK OFF
BET