Improvised inductor core ideas
I’m trying to make a loopstick antenna, so I need a rod shaped core
  for that and I’d rather not just order one on the internet.


Use a proper ferrite rod because it won't kill the signal like a piece of conducting iron/steel will. Consider the effects of induced eddy currents and consider that the insulation properties of a ferrite rod means that induced eddy currents will be very small. Why do you think ordinary AC transformers use insulated laminate strips of iron. Apply that thought process to the much higher frequencies used in radio communication. Don't bodge it.