In the summer of 1991, Dave Grohl went into WGNS Studios and recorded four songs, playing all the instruments himself. The recording was combined with six songs from a previous Upland Studios session recorded in late 1990. Although both sessions were recorded after joining Nirvana, Grohl unobtrusively acknowledged their existence. A tape of the songs, given to Simple Machines co-founder Jenny Toomey by Grohl, immediately became a candidate for the labels Tool Cassette Series.
The Tool Cassette Series started around 1991 as an experiment, and as a way of keeping music "in print" on an as-needed basis without having to finance vinyl or CD pressings, since Simple Machines dubbed the cassettes as the orders came in. With five cassette decks and a lot of volunteer help, this was a manageable project for the label. Shortly after Nirvana released Nevermind, its unexpected success was big enough that Pocketwatch became noticed. It gained even more exposure when the Foo Fighters debut was released in 1995. Some of the songs appeared on subsequent releases, creating even higher demand for the cassette. Suddenly, Pocketwatch was being mentioned frequently in interviews, and the label became flooded with orders.
With very little help and deteriorating master cassettes, Simple Machines got in touch with Grohl about releasing the Late! album as a CD, to keep up with demand. However, Grohl was more interested in keeping it as a cassette only release, which the label honored. When the two master cassettes for Pocketwatch came to the end of their useful lives, and with some of the other artists masters from the series in the same condition, Simple Machines decided to discontinue the Tool Cassette Series from their mailorder.