Another idea that might make use of one of the black fabrics (mottled or otherwise) is a stained glass type quilt. I've not made one myself (it's on my "maybe one day" list) but I understand they go together quite quickly because you can cut your coloured fabrics into larger pieces to make up your blocks. There's an old post by JNCT14 that feels like it might be a good starting point for this idea.
Wedding gift - stained glass quilt 