I sing with the Brooklyn Community Chorus and we sometimes hold our concerts at Congregation Beth Elohim in Park Slope. In return, CBE invites us to provide backup vocals during their High Holy Days services. I participated in 2019 and was pleased to receive a binder full of music, some of which was handwritten, heavily annotated, or used a different melody in rehearsal. To produce sheet music from these pages, I turned to Lilypond, a text-based music editor. In a few weeks I’d taught myself enough to transcribe 15 pages of music. The source files and PDF output are available on Github.