Does anyone know a nice, simple repetitive chant melody suitable for units of three lines? It could well be three plus three, but not 6 lines of three units of two, so to speak.

I know my vocabulary here leaves much to be desired….

Chant. How quaint.

I assume you're looking for something that can do three lines of eight syllables each. I don't know of an easy one.

https://www.saintmeinrad.edu/media/2837 ... _Tones.pdf

These are psalm tones based on the Latin Psalm tones. For Modes 1-7, you just use measures 1,2, and 6. For Mode 8, use the first line (the one with four measures) and do measures 1, 2, and 4. Does that help?