The neck bomb and gun looks like there are welds and there are a lot of shims on the collar. The 4 tumbler locks on the collar and what looks like a briefcase lock also make me think of a junkyard.
Again, the guy doesn't care about the "finished look" of his product, just its' capability. Obviously, the collar worked.
I haven't been following this mess -- do the reports appear to indicat that the delivery man was a perp or a victim???