It is quite unintuitive and inconvenient that only the Wand of Construction works with items put in the Big Backpack. And that neither the Wand of Space or the Wand of Architecture work with items from it.

I would even argue that the Big Backpack should take priority in terms of which materials to use first when using those two wands.

It would also be nice if the Big Backpack indicated that there were enough of a certain material to place them infinitely (like it shows in the Potion Bag)