scrap metal ideas + edf build


I found out there is a scrap metal yard near me with all sorts of copper/brass/iron/steel tubing and parts and old car batteries etc. Any ideas as to how I could use these in a diy cnc or hot wire cutter or another rc plane-related project? Does anyone know if you can scratch build a 3-blade or more edf style prop? Will something like this work:
Thank you!
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