Synthetic Flying Machine was basically collaboration between Will Cullen Hart and Jeff Mangum, with Bill Doss also being involved sometimes. The band would splinter off into Olivia Tremor Control (Will and Bill) and Neutral Milk Hotel (Jeff), but not before putting out at least one tape, Heaven Is For Kids. Many SFM songs later became OTC songs, and some are unreleased NMH songs. Jeff, by the way, did return to the fold and was a member of OTC in the band's early days.
Jeff: "Then we formed a band called the Synthetic Flying Machine. A lot of the songs we did in the Synthetic Flying Machine the Olivia Tremor Control do now, although when people say today "I really loved that band Synthetic Flying Machine . . .", it doesn't seem like it was a band as much as it was an extension of myself, and playing with Will was as natural as drinking water, you know? Also, Bill would come by and play guitar with us, he was living in Lousiana at the time. I guess we were sort of Neutral Milk Hotel as far back as 1989, a litttle noise/fuzz group, kind of a ramshackle attempt at being a band."