Everyone's building their own MIDI controllers these days. This is Richie Hawtin's, this was built for Monolake, who invented Ableton Live, and this is Andrew Neumann's MIDI Grips device, which he uses to improvise live music.
The easiest way to build your own is to use Doepfer's Pocket Electronic - a pre-built circuit board which you can attach sliders and pots to. (£59 from EMIS)
The next step - if you want to build your own sequencer, full-on control surface, or SID drum machine - is MIDIbox, a free collection of plans, operating systems and ideas. The gallery shows that pretty much anything is possible, given time and phenomenal geek power. The most incredible thing there is this vast control surface with motorised faders, a bit like a home-made Pro Tools Control 24.
DIY WEEK CONTINUES - CLICK FOR PART 3.5