cabinet converted to oven??

[afroEngineering]

Hello to everyone! I've been browsing the threads for a while, trying to figure out the most economical (I'm cheap-limited budget-and in college) way to make a decent sized oven. I surf craigslist.com and find free ovens out the wazoo, so used parts are abundant. I found this guy who was selling a "fire proof" storage cabinet for $25.00 so I went and picked it up. It had some surface rust in a few spots where the paint was chipping, but cleaned up nice after a good pressure wash. The label on the front said that the cabinet was FM approved, and MEETS OSHA REQUIREMENTS, model# 1947. Looked it up on the net, and come to find out, it's made from 18ga on both inner and outer skins, with a 1-1/2" space in between. It's heavy duty (347 lbs) and is the perfect size for what I want (65"x43"x18"). I was thinking about taking a cut off wheel, and slicing basically all the way around the top in order to bend a flap open, at the top of each wall. This way, I could fill the 1-1/2" gap in the walls with the insulation, bend them back down, and weld them back shut. Of course I would do this with the doors as well. WHAT DO YALL THINK? Will this work, or would I be wasting my time? please excuse the length-- I'm excited!