Steampunk Lazer Canon WIP

I found an old broken clock and decided to try to make a lazer canon out of it. This wil be mounted onto a leather or metal arm brace. I want to add a fuel canister with tubes that attach to the weapon, and also I want to design a firing mechanism that will wrap around the wrist and be in the palm of the hand. I have some ideas already on how to achieve this, but I need to think it through first. Here's what I have so far. I used the different parts of the clock to build the canon barrel and have begun to add embellishments to give it an older, Victorian feel.
I Photoshoped in the firing effect to show what it would look like if this were a real weapon.