Lowes or most hardware stores have clear plastic tubing for your circle, for the turret of the tower. They have a little piece that enables you to join the ends.I would use two panels and have the back slit the way its shown in the front in the photo.And as several have mentioned hang from the ceiling.Our Walmart here has that parachute type of fabric pretty reasonable.Oh, the fun those girls will have. Brings back so many memories,my sister & I had bunk beds built into the hallway, similar to the ones on the passenger trains and we hung blankets and would pretend we were on one. Good luck.