It is called a lift rod. Short description is a tee shape and the vertical portion goes up thru the bottom reel. Make a small loop on top, 1/4" diameter. The horizontal portion of the tee is diameter or a reel and one half is double piece that turns vertical. They can also be made from tubing with wire thru a hole in the in the bottom of the tube
Agitation is twisting raise i" , lower & twist opposite. About a 90 deg twist, not critical.
You get perfectly developed film.
If you can not find a lift rod, then stainless steel weld wire would be the proper material to fabricate.
I guess you can still buy them
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Put film reel lift rod in search engine. 8 reel ones can be cut down and new loop made. The 4 reel might be 35mm reels so you need the 8 reel