Apem buttons are of very good quality and they have a variety of sizes, colors, shapes etc. The have sand and water protection and to the extreme they sell silicon covers for the buttons
You can find some here http://export.farnell.com/jsp/search...D2012%2B203117
Browse for the buttons in the lower part of the page, some come with their own cabling which saves some time but it depends on what design you have in mind.
Avoid the ones with leds. They are fancy but (1) there is a reason for them and they are so bright you want to mask them before you break them
and (2) you need a resistor for the led to work. Otherwise you are just left with a normal button and a destroyed led. It happened to a friend of mine
Make sure you get the correct size, they come in two sizes from what I have seen. The Touratech and the lot use the smallest ones. I think the Touratech ones are not plastic, not the button itself, the case of it, the black thingy... You know what I mean
Nice billet work MakS ... It would be nice to create one billet for using two ICO's / IMO's .