Anyone built the super octave pedal?

[dubs]

Has anyone built the japanese super octave pedal on Mark hammer's site? Looks like a worthwhile build. Any thoughts/suggestions in building it?

[Maneco]

hi,
built two of these,added a fourt pot to mix original frequency square wave,tracks cool,i would be easy to add two octaves down with another 4013...i would like to add the diode ladder filter from electronics for music site,and some kind of envelope control

best,
Maneco