There are nine different colors of blocks which can be used to solve this puzzle as a Sudoku and produce this grid:
Read each set of colored blocks left to right, there are nine corresponding color words each with a letter inserted:
UCARDINAL LSAVENDER GUSNSMOKE DAFRFODIL CHARMCOAL VIRIDOIAN CERULENAN CHESTNUET FLAMINGOY
Reading the inserted letters left to right gives USSR MONEY which clues the answer RUBLE.