The hollow core door is a good choice. Just be sure it is FLAT. Being up in the rafters for an extended period of time may have warped it. Driving pins into the door is difficult at best. I used a product called Celotex for years. It is made of cardboard but is dense enough to hold "T" pins quite well. Another product is Homasote which is availabe at Home Depot or Lowe's. I've never used ceiling tiles so I can't offer much info on them. Take your door and overlay it with a piece of either Celotex or Homasote. Overlay that with your plans and cover them with waxed paper and you're off to the races. Good luck. NOTHING beats flying your own creation