So, my first eco seat ideas were these:
Using just one piece of the plank of wood & economical pattern of cutting. No waste, low tech, mountable. Almost DIY.
Using a bunch of reed, that creates needed conditions for sitting.
As the eco seat is also a study task at TaiK, both ideas I was discussing with my teachers & fellow students. Everybody agreed that the 1st idea is too usual, so the 2nd one seemed to be the way to go.