1/8" wow, that is beefy. I've long decided that bending is not my strong suit. I get my brass strip from K&S engineering (stateside) and the .063 would likely suit your needs for a similar construction. I used to use the thinner stuff and double it up for strength but .063 is plenty strong enough, and easier to bend.
edit: With your buttons, don't you want the ridge on the underside of the mod so that you can install it from the inside and it never falls off?