Well the basic suggestion is not new: A lot of us want the ground weapons to be costumizable.
The issue I see there is: I believe it needs a lot of server space if every we can save a costume on every weapon in our inventory.
But how about adding the weapons to the costume?
Every costume slot, bo and character slot, gets 3 additional settings: one for pistols, one for rifle, one for assault weapons. (best case: an additional one for a halftered pistol no matter if you really have one )
That way every rifle we use looks like the one set at the tailor ect...
Additionally, the weapons could have an enable/disable visuals-function (like the armor currently has) so if we enbable the visuals it shows the "original" weapon skin, if we disable it it shows the one set at the tailor.
Just as a little hint: Weapon skins WOULD SELL in c-store. The requests for Maco weapons or the original TNG-timeline weapons never seem to stop.