#top and bottom square of a corner post.
n64 addshape 2 4  0 0 0  1 0 0  1 0 1  0 0 1
n64 addshape 2 4  0 8 0  1 8 0  1 8 1  0 8 1

#outer two sides of a corner post
n64 addshape 2 4  0 0 0  1 0 0  1 8 0  0 8 0
n64 addshape 2 4  0 0 0  0 0 1  0 8 1  0 8 0

#the diagonal
n64 addshape 2 4  1 0 0  1 1 0  7 8 0  7 7 0

#side of yet another corner post I think.
n64 addshape 2 4  7 8 0  8 8 0  8 0 0  7 0 0