Ergotron LX Dual Side-by-Side Arm Cap Piece

The dual side by side arm came with a cap that you put on the joint to hide the inside, but that cap would not fit the product for whatever reason. Additionally, it looks like if you did somehow get it on you would not be able to disassemble the product as it has a latch which I have no idea how one could undo it. The stl is in 2 parts so that supports don't have to be used, though I included the fusion file if you want to export the stl as a single part