Closeup of the left side of the machine. The paper feed and pressure rollers can be seen here, together with their drive gears. The LED/phototransistor which senses when the paper has reached the folding position is also visible. The rollers are made from wooden dowels covered with rubber tubing, with short axles cut from 5/32" dia. nails inserted in the ends.

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.