Hi Steve, The Chimera volume path tracer tool can place markers which are spheres and connect them with cylinders. The spheres and cylinders can be made of small radius to make the outline of a cube. Below is an example XML file that makes a cube positioned at the origin with side length 1. You can change the x, y, z values to put it where you want it. When you open it in Chimera it will create a molecule model (it is implemented as atoms and bonds) and you can adjust its color, or move it relative to other models as you like. Tom --- File cube.cmm follows. Use the ".cmm" suffix so it is recognized by Chimera. <marker_set name="cube"> <marker id="1" x="0" y="0" z="0" radius="0.1"/> <marker id="2" x="1" y="0" z="0" radius="0.1"/> <marker id="3" x="0" y="1" z="0" radius="0.1"/> <marker id="4" x="1" y="1" z="0" radius="0.1"/> <marker id="5" x="0" y="0" z="1" radius="0.1"/> <marker id="6" x="1" y="0" z="1" radius="0.1"/> <marker id="7" x="0" y="1" z="1" radius="0.1"/> <marker id="8" x="1" y="1" z="1" radius="0.1"/> <link id1="1" id2="2" radius="0.1"/> <link id1="2" id2="4" radius="0.1"/> <link id1="4" id2="3" radius="0.1"/> <link id1="3" id2="1" radius="0.1"/> <link id1="5" id2="6" radius="0.1"/> <link id1="6" id2="8" radius="0.1"/> <link id1="8" id2="7" radius="0.1"/> <link id1="7" id2="5" radius="0.1"/> <link id1="1" id2="5" radius="0.1"/> <link id1="2" id2="6" radius="0.1"/> <link id1="3" id2="7" radius="0.1"/> <link id1="4" id2="8" radius="0.1"/> </marker_set>