[chimerax-users] Draw a circle

Hi, I would like to highlight a hole in a protein -the exit tunnel of a ribosome, to be more specific. I tried the command shape tube in order to draw three tubes passing through three residues, but the result doesn't suit at best my need and expectations. Is possible to draw a circle, passing through three points -or residues-? Do you have any suggestions? Thank you for your attention. Have a great week end. Greetings, Andrea