use_e = kppe + [0,-1] * slant * keeper_inner_width / keeper_slant_slope;
polygon([use_e + [+1,-1] * fatter,
kppd + [ 0,-1] * fatter,
use_e = kppe + [0,-1] * slant * keeper_inner_width / keeper_slant_slope;
polygon([use_e + [+1,-1] * fatter,
kppd + [ 0,-1] * fatter,