JONSBO N2 White NAS ITX Case - 5+1 Disk Bays Mini Aluminum PC Case with Built-in 12cm Fan, Supports SFX Power Supply (Max 150mm) & 65mm CPU Cooler, Removable Top Cover - Perfect for Home Media Storage & Small Office NAS Server Setup

This is the best small factor NAS case there is. I tried a few and this is leagues above the others. Build quality is great, almost all brushed metal construction. Style is timeless. Easy access to hot-swap drive bays. Good separation of mobo and drives. Good airflow. Easy to build. And takes a tiny amount of space. The only things that would make it even better are: 1 - A better built-in fan for the drives, I swapped it for a silent arctic cooling one. 2 - Slightly better layout that may allow for more space between the drives and fan, and perhaps the PSU. But this might come at the expense of the small size.