78mm Paper Core Adapter
thingiverse
Originally made for SLA prints. Print with hub connection facing towards plate. Light support structures should be sufficient due to a quite low adhesive slice area but depends heavily on your setup and resin. Depth/width of paper core can be altered by segmenting and extruding the adapter further. 10mm shaft to M6 thread to nut recommended. Add a set screw if you want to run it with flat shafts. Keyway is 3mm width and 17 mm in depth from hub end. Of course you don't need to use the whole depth to turn this but I made it for greater flexibility.
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