PlayStation 4 controller - R2 trigger has came off one of these little hinges (more detail in comments) : r/fixit
L2 R2 L1 R1 Trigger Buttons For Sony PlayStation 4 PS4 Controller DualShock 4: | eBay
Amazon.com: eXtremeRate Transparent Clear 2 Pairs L2 R2 Buttons Extention Trigger for PS4 Controller, Game Improvement Adjusters Extenders for PS4 Controller JDM-030 : Video Games
The PlayStation 4 controller: What's new with the buttons and triggers (part 3, exclusive) | VentureBeat
L2 R2 Triggers Ps4 (2 Pairs Trigger Extender,6Pcs Thumbstick Grips, 2 Pairs LED Light Bar