Any chance you can share the design spec, this looks awesome !
I would like one of those.
Well, it`s pretty easy.
I used this controller (supports only buttons, no axis, works out of the box. You plug a button in a prewired socket and it just works in Elite) ebay.com/itm/201123993135?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT (it fits perfectly in the case)
+ I used this case gainta.com/en/b025mfbk.html
+ different tumblers and buttons
ebay.com/itm/201224797333?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT (3 position tumblers, you connect two blue wires on the sides and one white wire on the middle)
ebay.com/itm/201243367608?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT (just connect each switch o a button place)
Also i used this connector for usb cable (if u want it detachable) !!!!! WARNING !!!!! SOLDERING NEEEDED !!!!!
ebay.com/itm/151062949360?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Big switches and their safe caps i ordered in my local store, not from ebay, but there is plenty of them anywhere.
Remove before flight tag and hama wiring management is really easy to find.
drilling scheme and labels you can download here: dl.dropboxusercontent.com/u/29210038/EG/controller/controller_renderg.pdf (note, that stickers are to be cut off, so their position is not actually as they are to be)
Sorry, i had to remove http, since forum won`t allow me to post links. 8)
Also the connector has few more slots, actually it is able to have up/left/right/down buttons + mode/turbo/etc buttons + one hat switch (also 4 buttons can be wired).