1

A crusader of the gun god. He covered the entire gun in engravings of his holy symbol

2

A witch. She decorated the gun with occult trinkets and iconography. (Like little voodoo dolls hanging from a string attached to the bottom of the gun.)

3

A racist wizard. The only way the gun will fire is if the wielder is the same race as the wizard, or at least wearing their skin as gloves. (I recommend choosing a monstrous race, just to avoid some of the uncomfortable moral choices. Unless you like that sort of thing.)

4

An Aarakocra warrior. Wind chimes hang from the barrel of the weapon. They only ring when the weapon fires.

5

An orcish war-chief. He thought he knew how to improve the gun. He didn't. The gun is just covered in sharp pointy bits of metal that he hammered onto it.

6

A romantic gunslinger. The back of the gun has a secret compartment with a picture of his beloved.

7

A Modron. He hated the chaotic nature of guns. All the sloping curves of the gun are turned into flat, geometric planes.

8

Nobody. This gun was freshly made and placed into the chest. Who made it is a better question...

9

A monster! The gun isn't in a chest, it's in the hands of an evil gunslinger!

10

A spacer. The gun is covered in a variety of bizarre and confusing gizmos. You don't really know what they do, but sometimes they make weird noises and flash red.