I had bought a dirt cheap used Fat (original) PS3 that worked, but the HDD tray and HDD was missing, I was looking for a upgraded HDD anyways, so I made a tray
...Plus based on a laptop drive that pressure fit the HDD into the PS3. I attached a piece of gaff tape to the drive as a tape tab to make for easy removal if needed in the future. The holes for screws were not used, the HDD pressure fits into the tray. Fits perfectly and works well.
