This is the horizontal portion of the Warp Core in the Enterprise from Star Trek the Motion Picture and Star Trek II: The Wrath of Khan. This piece was designed to go into the 1:350 scale Polar Lights USS Enterprise model kit specifically for a cutaway version. This piece is designed so it will slide up or down on the vertical Warp Core to correct for deck placement issues, and sit on the floor on Engineering Deck 15 running all the way back to the Warp Pylons. I also made the vertical section of the Warp Core which I had to upload seporately. I used pictures from the movies and cutaway diagrams of the ship to make the models.
The model can be viewed in 3D at SketchFab here: https://skfb.ly/6YIRI
The cutaway images can be found here: https://www.cygnus-x1.net/links/lcars/sd-constitution-ncc-1700-rebuild.php