The size and shape of a single stationary atom is described in the datablock .single_atom (that of a moving atom in .moving_atom). These datablocks are small ODL files with RELATIVE MOVE_TO and LINE_TO instructions for a graphics object called single_atom. By default, you get a cross of three lines, 0.4 A in length each. To change the size, just change all occurrences of "0.2" in this datablock to something else (0.5 if you want BIG crosses). To change the shape, change the set of MOVE_TO and LINE_TO instructions; there's an example in odat/icosa.o of how to make moving atoms look like icosahedrons. If you want your stationary atoms to look like this do:
O > read odat/icosa.o O > copy_db .single_atom .moving_atom
Now edit the .single_atom datablock and change:
Now redraw the objects that contain single atoms (e.g., water molecules).
Note that if you edit the .single_atom datablock, you must update the number of lines (and their maximum lengths) that are in the datablock:
.SINGLE_ATOM T 9 20
If you change the number of lines to 14, and the longest line is 35 characters, then change the datablock header to:
.single_atom t 14 35