Design a few icons for Chrome and Firefox extensions

Small project. We want to submit extensions to Chrome and Firefox's official repositories and we need icons for them. Icons should be similar (or identical) except for maybe the required sizes (which you can find out in their documentation, or we will provide to you if you win the bid - it's 128x128, 96x96 with some recommendations about edges and transparency). Also the icons are to be based on our already existing website style, so you don't need to invent much - just prepare nice looking icons based on the style and the recommendations from mozilla and chrome.