The Korg NTS-1 is an easy to build DIY monophonic digital synthesizer released earlier this year. The NTS-1 is also completely compatible with the logue-SDK*, so it is possible to run any custom oscillator and effect content available for minilogue xd and prologue, or, create your own.
Nick Kwas was on hand to talk us through the mini little synthesizer.
More info at Korg