This is a simple 2-stage optical vibe-effect for guitar. I've wanted one for quite some time and now I built it. Mellow and subtle. Not "over the top". This "design" is an adaptation of various Internet sources. Hope you find it usefull. I did. Here are schematics and a VERO-board layout (in EAGLE format):
optivibe_micro.sch,
optivibe_micro.brd