McDonald produced an album by The Format, Dog Problems, on which he played bass and sang backup vocals on a few tracks. He later produced, engineered, and mixed fun.'s debut album, Aim and Ignite, as well as performing as a bassist and backup vocalist on some of the songs. He was also one of the various band members on the original Tenacious D album, along with Dave Grohl; keyboardist Page McConnell of Phish; guitarist Warren Fitzgerald with band frontmen Jack Black and Kyle Gass. He appeared with Tenacious D on MADtv playing "Lee" and "Tribute". McDonald also featured briefly on bass in Kyle Gass' side-project Trainwreck in 2002 and 2003, under the pseudonym "Slim Watkins", before being succeeded by John Spiker.