solid tmp;
facet normal 0 0 1
outer loop
vertex 0 0 1
vertex 1 0 1
vertex 0 1 1
endloop
endfacet
facet normal 0 0 -1
outer loop
vertex 1 0 1
vertex 0 1 1
vertex 1 1 1
endloop
endfacet
facet normal 0 0 1
outer loop
vertex 0 0 -1
vertex -1 0 -1
vertex 0 -1 -1
endloop
endfacet
facet normal 0 0 -1
outer loop
vertex -1 0 -1
vertex 0 -1 -1
vertex -1 -1 -1
endloop
endfacet