I didn't have enough Meccano gears to drive three rollers spaced 1 1/2" apart in the same direction at the same speed, so improvisation was necessary. The gears and worms are from venetian blind tilter mechanisms, with collars made from electrical fittings and scrounged from various other places. The bosses onto which the nylon gears are pressed are cut from metal bolts, as is the special 5/32"-to-3/16" shaft coupler on the left.