He said "A free app with in-app purchases to export the result for 3d printing." Do you expect him to add an "export the result for 3d printing" feature without a payment model?
I am apparently being misunderstood. I don't mean to imply that including a feature for exporting models is a bad idea. But I don't understand why it's controversial to take advantage of platform's payment service for actually printing those models as physical objects and sending them to users. Obviously one would not do that for free.
