According to some embodiments method for making an optical fiber preform comprises the steps of: (i) placing a plurality of rods with an outer surface having a coefficient of friction 0.02≤COF≤0.3 into an inner cavity of an apparatus; (ii) placing particulate glass material in the inner cavity between the rods and an inner wall of the mold cavity; and (iii) applying pressure against the particulate glass material to press the particulate glass material against the plurality of rods.