Add voxels to fill a box between the two coordinates.
add s box x,y,z to u,v,w
s sprite name x horizontal y vertical z depth u horizontal v vertical w depth
Source create sprite 6 as "cubes" color 1 add "cubes" frame 1,1,1 to 6,6,6 color 2 add "cubes" box 2,2,2 to 5,5,5