Why you cannot re-sell a needlework design that you have bought in electronic format (eg. pdf)
1. A Digital File that is being distributed is being REPRODUCED.
2. The Copyright Owner is the only one that has the right to REPRODUCE a copyrighted work, or to prepare a derivative work.
3. The First Sale Doctrine applies to those works such as videos, books, etc. where copies were legally purchased.
In the case of a Digital File, these are reproductions of original copyrighted works, and so the Copyright Owner is the only one that has that right to reproduce them.
Subject Matter and Scope Of Copyright, Section 106, "Exclusive Rights In Copyrighted Works" (Pages 16-17: Section 2, 3)
"106 · Exclusive rights in copyrighted works
Subject to sections 107 through 122, the owner of copyright under this title has the exclusive rights to do and to authorize any of the following:
(2) to prepare derivative works based upon the copyrighted work;"
(3) to distribute copies or phonorecords of the copyrighted work to the public by sale or other transfer of ownership, or by rental, lease, or lending;"
The US Copyright Office is the final authority.