As far as I know, only a handful of D*A*M FZ-678 were ever made, maybe 5 in total - it's a variation on a Zonk Machine.  It's the same structure as a Zonk, but with a fitler attached to the input.

I haven't made a layout for it, as it's all there to see - and I could not imagine that anyone wants to build one using this format.  If you want to make one, I'd say just use your favourite Zonk layout, and tune the filter to your liking.  Like all things Zonk / MKI - get it on the breadboard first.

D*A*M FZ-678

There's still a couple of things I'm unsure about on this, as there's very few photos available, and the colour coding on blue metal oxide resistors is misleading.  example:  the 470k resistor looks like 5m7  

Link to Stompboxes site.   Transistors: Mullard OC42, OC44 and OC83 (Q1, 2, & 3).