Something like the Bit Commander or Octasynth

[Shawbrook]

Are there any diy projects out there similar to the Subdecay Octasynth or the Earthquacker Devices Bit Commander, so a synthy (fuzzy) octaver?

[nocentelli]

Search for "Shocktave" for a nice simple fuzzy sub-octave circuit.

[slacker]

Or slacktave

You'd need to add a filter of some sort to get somthing more like those pedals though. For something more advanced google mfos subcommander

[Shawbrook]

But these are only octave down, right?

EDIT: Nevermind, so is the Octasynth. Thanks for the suggestions. 

[slacker]

There's a mod for the slacktave that adds an octave up, a forum search should find it.