Craft box assembly

QuestionsCraft box assembly
Mini asked 9 months ago

for my first Amazon product, I am putting together a craft box with items sourced from different US and CN manufacturers (Think of a rock painting set with multiple little sub items – paints, googly eyes, rocks etc)
Knowing about tiptrans was super valuable — thanks for that!
It is a difficult first product to launch, due to the complexities around dealing with multiple suppliers.
I do not know how(or who) I am going to  assemble the box, put in the sub items and have it ready for amazon.
Are there companies that help with that? How do I overcome the problem of having some items coming from US, some from CN?