I absolutely loved the conclusion to "Breaking Bad" last night but one thing has been nagging at me. Walt built an extremely complicated machine-gun-firing device in - what? - one afternoon? The trigger was rigged to the trunk latch, it had a vertical-rising table, and an oscillating arm. This wasn't exactly an Erector-set contraption since the recoil from the M60 would be significant. I just think it would have taken an MIT engineer about a week.