I support the basic idea of this thread, however...
I disagree with the idea that each component of a weapon should have to be produced seperately and then assembled in an additional reaction; or at least I don't support that as the only option for assembling weapons (I will explain what I mean shortly).
I would prefer to be able to call for the entire weapon to be built at once by first selecting the type of weapon to be built from the menu for the relevant workshop, and then selecting materials from which to build each part of the weapon from a series of additional menus that would then come up, in a manner similar to that currently used for constructing buildings, walls, and traction benches. Now, the only problem with my proposal is that it could not be handled in the manager screen without overhauling the interface, and so for this reason it would by necessity have to exist side-by-side with something more similar to Max's original proposal.
The basic idea, however, is completely solid. personally I believe that, (possibly in combination with some custom reactions) it would help relieve some of the shortfalls and limitations that were introduced as a side-effect of the current weapon system (it could, for one thing, allow heat and cold based custom weapons to be re-instituted without burning or freezing the wielder)