Ash's Boomstick from Evil Dead 2 / Army of Darkness / Ash vs Evil Dead.
Although referred to as a Remington in Army of Darkness the shotgun used is a Stoeger coach gun.
Full credit to the creator of this model, "Rabid Beagles" which I found on Sketchup 3D Warehouse. He has a bunch of awesome models with great detail that can easily be modified to 3d print.
To make it a little more realistic I added a hinge point, which will require inserting a screw or metal pin to act as the pivot point. From memory I used one of the little metal pins that are discarded after using a pop rivet. I just cut it to the appropriate length and glued over the hole on the outside once the pin was inserted.
I cut small slots to insert small but quite powerful magnets top and bottom to keep it closed but still allowing it to be easily opened.