Optically, sonically, haptically fuzzy. The Foxx Tone machine was the first* fuzzbox to tickle three senses simultaneously, best known as it was for being covered in brightly coloured flocking. Sadly it is lost to history whether a scratch'n'sniff feature was ever offered or not
Tactile gimmicks aside, the Tone Machine would have been a collector's curio had it not so successfully lashed an upper octave effect to a very thick, diseased fuzz. Octave fuzzes had been around for a few years by the time the TM showed up in 1971, but it definitely had plenty of its own character to stand out from what was already available.
This rendition sticks pretty close to the original circuit - adding just a couple of tweaks to cut down RF interference, and making upper octave foot switchable (very handy for live happenings).
What's it sound like? Well, without the octave switched in, it's a very thick Muff-ish sound - fat and doomy on chords; rough, almost ripping velcro on single notes, with a great unfocused, dying battery type decay that begs for a bit of vibrato. Kick the octave on, and it tightens up a lot - like throwing a light switch in a darkened room. The tone knob proves handy to dim it down a touch if it's a little too bright for your taste.
The upper octave is really pronounced (much more so than say, a Super-Fuzz), but never overpowers the fuzz content. Way beyond something you'd only use for "that bit in Purple Haze". It does, though, do a cracking impersonation of the Roobarb theme...
*There may be an earlier claim to the be the first flocked fuzzbox. A V1 Univox Super-Fuzz in bright green flocking showed up on eBay a few years ago, with the seller claiming he'd had it made as a one-off in the late 60s after a chance encounter with a Univox sales rep at a local guitar shop. True or not, I don't know, but still a nice story.