My favorite method of masturbation is standing at an open window in the back of my house that looks into a workshop attached to the house. With the exception of two of the windows in the house, all the sills are 4 feet high and I can easily stand at the windows and rest my elbows on the sills. A 2x4 stands under the sill against the wall with the base of the 2x4 about 18 inches from the wall. When I masturbate I straddle the 2x4, lubricating it with saliva and sometimes KY jelly and hump it, raising myself up and down by standing on my toes and thrusting my hips, fucking my cock between my belly and the 2x4.
In the shop, against the wall of the house, there is a parts cabinet the same height as the window sill on which I can rest my portable device I use for watching porn and anything else necessary such as cigarettes, ashtray, lipstick, masturbation lubricants and sex toys. Using this method I've been able to masturbate and achieve orgasm even when my penis is limp or semi-erect. This is also fun way to play with a boyfriend or gurlfriend as they can get behind me and fuck my ass, holding my hips or rubbing my big boobs as I'm masturbating.