What length pipe or tube should you use?

Giza Pyramids create a larger footprint which means  for it to be tall enough to sit under you need

a large base. The smallest an average size adult would use is around 150 cm x 150 cm or 5 ft x 5 ft base. This gives you a total height  of around 1 metre or  3 foot 3 inches. As  the  size of the base increases so does the overall height and always in proportion to the sacred geometry. 

Nubian and Russian Pyramids  have a smaller footprint but are much taller so ceiling height  needs to be taken into account.  To fit under an 8 foot or 2.4 metre ceiling this Pyramid style will have a base no larger than 136 cm x 136 cm 0r  4 foot 5 inches.

You need to decide what space you have available and  I can help you make the simple calculation to cut the your pipe or tube to the correct length.