4x5.25" to 5x3.5" drive bay adapter

thingiverse

A versatile 5.25" inch bay to 3.5" HDD adapter, perfect for expanding storage in systems with up to 4 bays. Print two copies of the frame size you prefer and secure them to your case using a few M3 screws. Then, simply slide your hard drives into place, where they'll be held snugly by friction while still allowing for excellent airflow. The design accommodates a variety of bay configurations, with versions available for 1x, 2x, and 3x bays. However, it was primarily designed to support systems with 4 bays. If you're in a hurry, I've also included a half-depth lite version that's perfect for those who can't wait. While I haven't personally tested this model, it's ready for you to try out whenever you're ready.