The one thing I hated about Agent Mouse was the fact that his chest armor was bright blue. I gave it some silver wash to make it metallic and then dry brushed some black over it to make it look battle worn. Very simple, but now I like my Agent Mouse a lot better.
Someone suggested using Ult Flint's black helmet, so I went through my parts bin and realized, I actually have a black Ult Flint helmet in my spare parts bin so I don't need to take it from my complete Flint. Here's how he looks like with his 'twin' Scoop.