If you add a low/high price estimate, I'll probably give it a new try.
You can also probably add a "Is this item fragile" as an option to add less or more padding.
Also I send 3 boxes of the exact same size, it would be great in your app to be able to duplicate items (I had to create one big package by adding the height and weight all together, was too lazy to create 3 different ones, or 2 in a extra large and 1 in a large)
I sent an email to the support and got refund a bit. (all the boxes I shipped were the same size, but I don't know why they were slightly different for all of them in the confirmation email I received ..)