I added a Chimera command "scolor" that can color surfaces radially or according to volume data values such as electrostatic potential. This command is the equivalent of the Surface Color dialog. A few examples: scolor #0 geometry cylindrical colors the surface by distance from a cylinder axis (default z-axis) with default coloring red-white-blue ranging from minimum to maximum surface radius. scolor #0 geom radial cmap 100,gray:150,blue:200,purple colors radially with colors gray,blue,purple at radii of 100,150,200. scolor #0 volume #1 cmap -10,red:0,white:10,blue colors surface #0 using volume data #1 with colors red,white,blue for volume data values -10,0,10. Here's a summary of the full command syntax. Detailed documentation will be available in the manual before the next Chimera release. scolor <surfaceSpec> [volume <vspec>] [gradient <vspec>] [geometry radial|cylindrical|height] [color <color>] [center <x,y,z>|<atomspec>] [axis x|y|z|<x,y,z>|<atomspec,atomspec>] [coordinateSystem <modelid>] [cmap <v,color>:<v,color>:...|rainbow|gray|redblue|cyanmaroon] [cmapRange <min,max>|full] [reverseColors true|false] [colorOutsideVolume <color>] [autoUpdate true|false] [capOnly true|false] [perPixel true|false] Tom