I have a large Lilypond project for several hymnals. The project is organized into a subdirectory structure with each hymn in a separate directory. For each hymn I produce several products: an 8.5x11 PDF, a 6x9 PDF, a set of images formatted for projection at 4x3 and 16x9 aspect ratios, and a set of part dominant MP3's for use in learning the hymns. These products are then assembled at a higher level into a comprehensive PDF of the hymnal including front material and index; and a package of the slide images organized to be compatible with a Slide production product used at my church for assembling a song service; as well as assembling metadata files to be uploaded into a website I maintain that provides access to these hymns and provides simple search capabilities and internet access to these products.
I use Make (that old workhorse) to automate the process; but that has some distinct limitations. So I was wondering what tools others may be using to aid them in building larger Lilypond projects. What, if anything, are you using? How well does that work for you?