i've noticed there are a lot of people asking lately how to attach the earcap to the helmet and the rf to the stalk; whether they've pm'd me directly or asked in a thread. so i'm here to help out with that, and show off how i do this.
first off, i usually do this part after i've pained the helmet and the earcap. you have to be a little more gentle with it when you do it that way, but it's do-able. if you're not comfortable waiting until that stage to drill through your helmet you can also do it at an earlier stage, but just make sure the earcap has been cleaned up at least.
so i start with the back of the ear cap and i bore out two sink holes with the Dremel 9901 Tungsten Carbide Cutter, make them just large enough to sink the head of a flat head 6-32 x 3/4" machine screw into. you don't have to go too deep, probably less than 1/8", just get in there deep enough so that the angled edge of the head isn't above the plane of the ear. once you have those placed i use 5 minute epoxy to hold them in.
like so -
next i eyeball line it up on the helmet and use the screws to scratch into the paint where i'll need to drill. i think i used a 1/4" bit, i drilled out the spots i scratched with the screws. line the holes up with the screws and see if it sets right in. if it does, AWESOME!!! if it doesn't, then get your dremel out again and use that bit i suggested to bore out the hole a little bit in the direction you need it to go to get the screw sitting in there right.
then once the ear sits all nice and pretty you attach it on the inside with a #10 washer and a 6-32 acorn nut (my preference is for the brass, but you can get them in stainless).