A cardboard box that comes flat and one must then fold it into it’s box shape (without using tape): May this be done on Shabbos for the first time? What if it was already done once in the past and the box was put back into it’s flat shape and someone now wants to open it up again to form the box.
Answer:
It appears that both actions are prohibited.
Forming the box is a case of makeh be-patish, completing the formation of a utensil, such as inserting shoelaces into a shoe, or feathers into a pillow.
Although in the cases above it is permitted to re-insert the feathers or the shoelaces after they fall out, the reason for this is that the shoe is not considered to be “broken,” but rather temporarily out of use, and restoring it is not considered a significant action. It is “maintenance” rather than formation.
In the case of the box, this does not appear to be the case: Once flattened, there is no box at all, and re-forming it will once again be makeh be-patish.
