ok pics time ! 
In the beginning it started with 2 buttons that via the arduino usb cable and a software Serial2Midi converter, it performed simple MIDI on off
Then it grew up to be 1 multiplexer wired with 6 pots and those same 2 buttons
Then the desire of more buttons and knobs came and a diy arduino shield was born (Such a genious board arduino is, such a stupid error to make the spacing awkward :-/. With longer headers and some crafty bending its fixable.)
This is the final layout, box is made from 3mm thick very dense fibre board i found on the street. (Someone had thrown away his kitchen drawers and stuff)
Everything in place ready for soldering. It looks like a mess, but i prefer to call it controlled chaos 
Close up of the circuitboard - 10 debounce circuits for the 10 buttons
Everything soldered in place
And the box closed.
Here is the code for the midi controller.
Here is the debug code for the controller, helps alot.
If someone wants the schematic, let me know.
I know everything is not fancy and shiny, but hey thats my first box i made and the first arduino project i made.
Many thanks to Addidis for helping me go through all of this
http://www.jeselectronics.com/
ps. sorry for the pics being as url but they are too big.