profile p x 4 y 1 x -3 y 3 x 3 y 1 x -4
prism pr p 0 0 1
explode pr f
profile pp x 0.5 y 0.5 x -0.5 y -0.5
trotate pp 0 0 0 1 0 0 90
ttranslate pp 3 0 0

featprism pr pp pr_1 0 1 0 0 1
featperform prism result pr_7

set square 47