Construct twelve spheres of the same size each touching four others.

> restart:

> with(plots):with(plottools):

Warning, the name changecoords has been redefined

> x1:=sphere([0,1,1],p,color=blue):

> x2:=sphere([0,1,-1],p,color=yellow):

> x3:=sphere([0,-1,1],p,color=red):

> x4:=sphere([0,-1,-1],p,color=green):

> y1:=sphere([1,0,1],p,color=gray):

> y2:=sphere([1,0,-1],p,color=pink):

> y3:=sphere([-1,0,1],p,color=cyan):

> y4:=sphere([-1,0,-1],p,color=brown):

> z1:=sphere([1,1,0],p,color=coral):

> z2:=sphere([1,-1,0],p,color=magenta):

> z3:=sphere([-1,1,0],p,color=orange):

> z4:=sphere([-1,-1,0],p,color=violet):

> a:=display(x1,x2,x3,x4,y1,y2,y3,y4,z1,z2,z3,z4,scaling=constrained):

> a;

> vrml(a,"c:/042/9/9-13.wrl",background_color=white);

>