re-user; person who repurposes
Refers to someone who takes an existing item, material, or idea and uses it for a different purpose than originally intended. Often used in contexts of recycling, upcycling, or creative reuse.
He is a repurposer of old furniture; he turned a chest of drawers into a bookshelf.
This app provides information for re-users who turn old cloth into cleaning rags.
再利用者 is a more general term for someone who reuses something, often without changing its form or purpose, whereas 転用者 implies a change in the intended use.
Compound of 転用 (repurposing, diversion) + 者 (person). The exact historical derivation is uncertain, but the kanji components are conventionally associated with the meaning.