A remix from Smokhov's Spool holder, looked like a great idea, but the extension cord I have was a different type. So starting from their design I remodeled the parts in Fusion 360 and made some adjustments.
This models work with Amazon basics or Overture spools.
I expect other people will have the same issue that I did with their extension cords not being compatible. So, I also uploaded the Fusion 360 files for anyone who wants to make changes.
Cut a hole in the inner part of the spool large enough for the plug of the extension cord to fit through. Pass the plug end though the hole and then through the center on the spool. enclose the plug end in the hafts of the core and press it into the spools center.
The Cord clip is press fit into the hold on the outer edge of the spool.
The author marked this model as their own original creation.