Lohner can frequently be found contributing to movie scores with fellow Nothing Records alumni Charlie Clouser and Clint Mansell. Additionally, he does remixes for various artists under the pseudonym Renholdër (an in-joke anagram of Re: D. Lohner). This began as a result of the song of the same title, which appeared on A Perfect Circle's debut album Mer de Noms. Contrary to popular belief, Lohner did not work on this song but was later told by guitarist Billy Howerdel that the song was about him. He has appeared in all of A Perfect Circle's albums to date in one form or another and has also appeared on stage with the band.
In early 2003, A Perfect Circle's official Web site announced that Renholder would be replacing Troy Van Leeuwen as the band's second guitarist. While Lohner did receive production credit on the band's second release, Thirteenth Step, he had other obligations by the time touring began, and ex-Smashing Pumpkins guitarist James Iha stepped in to fill the void. The most notable reason for Lohner's departure was his obligation to produce the soundtrack of the movie Underworld. This soundtrack was a collection mostly consisting of tracks written, produced, remixed, and performed by Lohner and his friends in the industry, including David Bowie, TRUSTcompany, Maynard James Keenan, Johnette Napolitano, and others. Lohner worked with Richard Patrick of Filter, Wes Borland of Limp Bizkit, Black Light Burns, and Josh Freese of A Perfect Circle and Nine Inch Nails, in a project called The Damning Well. A total of 14 songs were recorded, but only one of these made the soundtrack. So far, there have been no plans to release the rest of the songs.
In November 2004, Lohner contributed heavily to eMOTIVe, the third full length album by A Perfect Circle. This album was mostly a collection of cover songs, but it also included "Counting Bodies Like Sheep to the Rhythm of the War Drums," a continuation of "Pet" from the band's second album, Thirteenth Step. In addition, there was an original work, titled "Passive," which was the final version of a song originally composed for the Tapeworm Project. This track subsequently appeared on the soundtrack of the film Constantine, and Lohner appeared in the video for this track. A sister to eMOTIVe, 2004 also saw the release of aMOTION, a 2-disc collection that included a CD of the band's remixes and a DVD of music videos and live material. The remix album included Lohner's remixes of "3 Libras," "Judith," "Weak and Powerless," and "The Outsider." Although these remixes had previously been available on various soundtracks and CD singles, 3 Libras was reworked slightly from its original release, and "Judith" now featured censored lyrics. On both eMOTIVe and aMOTION, Lohner was credited as a band member.