Input: green slider. Its violet pin is fixed to blue belt
Output: pink slider.
Yellow slider moves in slot of the pink slider. Red pin, which has revolution joint with the yellow slider, is fixed to black belt.
When the green slider moves to the left, the pink slider performs reciprocating motion.
When the green slider moves to the right, the pink slider performs the same reciprocating motion.
Output motion can be adjusted by altering diameter of the small pulleys.