Not long after the release of Garry's Mod 13, I made an Amnesia: The Dark Descent lantern mod. Back then I had little 3D modeling and animation experience, so I used a tool called SWEP Construction Kit that allowed you to take an existing viewmodel and to attach extra models to it. I used this to replace the Half-Life 2 pistol viewmodel with a lantern, then I added a dynamic light to it and upload it to Workshop. This addon was relatively popular, but its grunginess is unavoidable. Many years down the line, after getting a lot of modeling and animation experience, I decided to remake the entire addon from scratch.
The result is a SWEP which looks and plays just like the lantern in Amnesia. One feature I did add that wasn't in the original, however, is the jiggle physics. In the original game, the lantern would bob around, but this was all done through animations. My version of the lantern has a jiggle bone, which makes the lantern realistically always point towards the ground (and this is also the case for the worldmodel). The addon comes with two versions of the lantern: one that requires constant refilling with oil, and one that has infinite oil.
This addon is one of the most popular weapon addons on Garry's Mod's Workshop, likely due to its use by pretty much every medieval themed server in the game.