From as early as 1969 Pink Floyd experimented with non-traditional musical instruments to create new sounds and, in a way, new music.
From this time until their heyday in the mid-seventies, the lingering idea for an album comprised of this kind of "music" entitled Household Objects remined in the back of their minds. The idea almost came in to fruition following the success of Dark Side of the Moon, seeming a viable solution to the pressure of releasing a successful followup. However, luckily(?) the idea was shelved and the band released the legendary Wish You Were Here instead.
There are still remnants of the ideas floating around in the Floyd's catalogue, in Atom Heart Mother's "Alan's Psychedelic Breakfast," the long drone-like intro to "Shine on You Crazy Diamond," and a couple of other cuts released on recent box sets.
Check out an entire article on the lost Floyd album here