Canadian Artist Living in USA Research Question

I'm hoping someone here can help me. I am an author residing in the United States and the book I am working on features at Canadian sculptress who visits the United States to regroup and possibly start working on a new piece. She is financially independent and is not working for a company or any particular individual. My question is if someone commissions a sculpture from her and she creates the sculpture in the United States, how would she be paid being she's a Canadian citizen? A commissioned sculpture can be well into the thousands and I would assume there is some form of a tax implication. I looked under work visas but nothing applies to an individual artist working for themselves.

In the story I have heard visiting Florida for a couple weeks, but then she's asked to create a sculpture while she's here. This extends her stay a couple months.

Any help at all would be greatly appreciated.

Thank you,
Amanda Renee