default bottom_w = 0.6
default bottom_dx = 0.1
default bottom_height = 0.3
default base_height = 1
default base_w = 0.2
default top_w = 1.2
default top_dx = bottom_dx
default top_height = bottom_height
default base_dx = bottom_dx

H bottom_w ;
l bottom_dx, bottom_height
H base_w ;
l base_dx, base_height
H top_w ;
l top_dx, top_height
H 0 ;