I have recently started using sketchup as a hobby, and to put my ideas on "paper". I have started out designing my back yard deck for me and my dad to build next spring. I have also just started designing a concept/practice design, similar to the communicator on Leila's arm (from Futurama). My first question on this forum, is basically, how would I go about indenting a smoothed surface? Imagine a cylindrical lighthouse, I would like to put a parallel indent to maybe make room for a window or door. Any help is appreciated.