Materials:// solid wooden plate (exterior) // veneer , plywood, carton (interior) (+ metal lock, handle and hinges)
most of the time standardized sizes, or produced in big amounts (standardized sizes 78x201cm, 83x201cm, 78x211cm, 83x211cm, 88x211cm, …)
at demolition sites, recycling websites (like GlobalRecyclingNetwork) give references where else to find these used material
Bellydancing BILLY: https://www.superuse.org/story.php?title=Bellydancing-BILLY
Only by putting the used door horizontal on top of some trestles, the door obtains an other use.