I decided to build my own feedback loop after doing some reading and studying the layouts over on Beavis Audio and so far I'm pretty happy with the results:
Everything used came from PedalPartsPlus to the tune of about $17 plus shipping. Since there is no LED, no power is required making it a VERY simple build. Originally I was going to do it in a 125B enclosure but I opted for a very nice 4SITE 1290 enclosure that was pretty nicely done. Something makes me want to try and squeeze this into a 1090 enclosure, but I'd have to go to a slightly less heavy-duty switch to make it all fit.
The schematics on Beavis listed a 500k audio pot, but I may play around with this a bit. Something doesn't seem quite right - the effect isn't coming into play where I think it should - but for now it works well enough.
Why the zombie unicorn? No idea. Clearly I have issues.