Let the customer fill the box
Every bundle app I looked at decides what goes in the bundle. The shop picks six things, calls it a hamper, and the customer buys it or does not.
Packhouse hands that choice to the customer. They pick a size, dress it — ribbon, card, colour, whatever the shop offers — and fill it from the shop’s own products. It arrives in the basket as one line at one price, and on the order as a list of exactly what is inside.
That inversion is the entire product, and it is worth saying plainly because it is also the two searches nobody has a good answer for: build your own box and create your own hamper.
Capacity is counted in units, not items
The first thing that broke my assumptions. “A box holds six things” is wrong the moment a shop sells both a celebration cake and a bar of chocolate. So a box holds a number of units, and each product says how many units it takes up. A cake can take two places where a bar takes one.
It sounds like a small piece of arithmetic. It is the difference between the feature working for one shop and working for a trade.
Changing your mind is the hard part
A half-built box is remembered if someone comes back to the site. A finished one can be reopened and edited from the basket, rather than removed and started again from nothing.
Neither is glamorous, and both took longer than the building itself. But a box is a thing somebody spends five minutes assembling, and five minutes of work that a mistimed tap destroys is not a feature, it is a reason to leave.