So I have a 25-year veteran graphic artist, he's really good at it and gets paid for it during his day job. He does anything I want for free even though I offered to pay him. He's designed me some shirts for Teespring and they've sold well., he won't take any of the profit. So how would y'all go about monetizing this relationship? I told him I can be the one to advertise his services and we would split the profit, even though I don't think he will take any. Should I just stick with t-shirts or try other things? Thanks.