After picking up an M3 MacBook Air, instead of getting rid of my mid 2015 MacBook Pro I decided to upgrade the operating system with OpenCore Legacy Patcher and I confirmed the old laptop is still perfectly usable for every day (non-power user) tasks. I needed some extra room on my desk in order to keep it around and this mount allowed me to do that. These mounting brackets are well designed for 3D printing; they can be printed without supports unlike some of the other ones I came across on Printables and elsewhere. My remix allows access to all ports except the headphone jack (which is redundant given the digital audio outputs on my dock and monitor). I printed mine in PETG with 40% infill, fastened it to the underside of my Ikea desk with cabinet screws, and it seems plenty strong enough to hold the laptop securely.
The author remixed this model.
Modified to fit MacBook Pro (Retina, 15-inch, Mid 2015)