ICY DOCK Announces 24 Drive ToughArmor MB924IP-B Backplane | TechPowerUp
 
The ToughArmor MB924IP-B supports 24 x 2.5" SAS/SATA SSD/HDD up to 7 mm in height and only uses 3x 5.25" device bays. It has 6x MiniSAS HD (SFF-8643) connectors in the rear to support 24 x drives with up to 12 Gbps transfer speed per drive, significantly reducing the cable clutter to improve system airflow and offer easy cable management. The large 80 mm fan with 3-Mode fan speed control working along with intelligently placed ventilation holes keeps your drives in optimal temperature. To further improve reliability and security, the housing and trays are made with ruggedized full metal construction to ensure long-lasting durability. Moreover, with the removable EZ-Slide Nano trays, you can interchange drives within seconds without open the PC case.

MB924IP-B connects 24 x 2.5" SAS/SATA SSD/HDD with only 6x MiniSAS HD (SFF-8643) & 6x SATA 15 pin power connector for easy cable management and better system airflow. These are essential for high-performance PC builds. The MB924IP-B supports data transfer speed up to 12 Gbps per SAS drive and 6 Gbps per SATA drive.
 
This looks like a great way to build your own NAS