Thinking through an exporting event in Three Land:

Working column by column beginning with the smallest blocks,

Fig. 1: Must put two Unit Cubes in the truck but only have one, so trade one Long for three Unit Cubes, resulting in four Unit Cubes, leaving one Long and two Unit Cubes after putting two Unit Cubes in the truck.

Fig. 2: Must put two Longs in the truck but only have one. Would like to trade a Flat for some Longs, but do not have any, so trade one Super Cube for three Flats and one of the Flats for three Longs, resulting in four Longs, leaving one Super Cube, two Flats, and two Longs after putting two Longs in the truck.

Fig. 3: Do not have to put any Flats in the truck, so left with two, but must put one Super Cube in the truck and have just one so left with none.