Congrats on making your game into the jam! A few ideas to improve the experience:
-Add sounds to every gameplay action: some cardbord stretching noise on scaling the box, a click when picking objects(and maybe different ones if they are made with different materials), etc
-Add an objective to accomplish: maybe getting all the objects in the box with the smallest box possible, or maybe arrange correctly the items in the box so they cant be broken when shipping the box to some place.
-Add level passed messages when all the items are in the box, and level failed messages when lets say a timer runs out, or the items broke inside.
Anyway, great job and congrats again! :)