The way I have been working for this track and for a number of years now is to start with field recordings. At Lanternhouse I recorded a host of sounds from kettles boiling, the lift going up and down, banging on handrails, playing the instruments in the music room, anything that catches my ear really. This was done with binaural and contact mics. I then use an audio editing programme to find small interseting parts of my field recordings to chop into loops - it may be that the rhythm is interesting, there's a kind of melody, or is just plain weird. I then have a bank of loops that I can then improvise with.
Lanternhouse I features piano, hamonium, traffic noise, fridge, fire extinguisher and hand rails.
I will be releasing the Lanternhouse field recordings as a remix pack so everyone can have a play with the sounds, I will feature some of the best on the blog - let me know if you're interested at firstname.lastname@example.org