We’ve experimented with dildos, vibrators, various fruits and vegetables, wine and beer bottles, a baseball bat, hair brush handles, the post on the footboard of a bed, the gearshift knob on a car, a set of plastic balls, an improvised ice ‘dildo’ and the barrel of a toy ...... (during some kink play).
My favorite is something we call the “banana trick” - a thing KK picked up on from a dirty novel during our college days. She uses a slightly green, unripe banana (because it is firmer), peels it, and gently fucks herself with the banana until her orgasm mashes it. Then I get to clean up the remains - a pussy juice “banana split."