This is the clone I built of the Dan Armstrong Green Ringer. It was not even originally a pedal but plugged direct into the guitar jack. That would explain the lack of pots. It may be the simple but it is the best octave(more of a ring modulator in reality) type effect i have heard. Not that difficult of a build especially with a pcb available at GGG. It is housed in a pvc drain cover. The idea came from Amzfx and I complete forgot about it until i was milling around Home Depot. They're cheap and pretty tough. They can be shielded with aluminium foil or copper tape. I added a grate that fits inside of the bottom which should protect the components better. I cut a cardboard circle out to fit inside the grate piece and wrapped it in foil. I have not have an interference problem with it at all. If you want to mount the jacks on the sides you'll have to trim the top of the grate off which should not be a big deal. I painted it green originally but decided to it should look more like a ufo which I don't think I pulled off so well. I am sure better results can be had. One problem cosmetically with the drain cap is that there is writing raised up on the cover which is pretty unattractive in my opinion but it can be sanded off or coated over.
I think I might wrap the whole thing in foil and add ten more leds and some antennae. Now that would be a ringer for a ufo.