I wanted to make a Raspberry Pi NAS in a chase
The chase wolud hold two harddrives and connection extentions for Ethernet, USBs and the HDMI mounted on the chase.
The hdds had to be easy to change - Thats why after serarching on the web I found the ToughArmor MB992SK-B witch could hold 2 hdds only needet one power conector and ofc hard 2 sata one for each hdd.
Now the problem was how to connect the PI to the ToughArmor MB992SK-B - for this I found a Sata to USB adapter with power supply and with another another Sata to USB adapter problem solved.
Or so I tought - this would take two of the four USB avaible on the PI and I wanted 3 free USBs on the chase one for a wireless reciever to connect to mouse/keyboard and two free for other devices souch as a WiFi dongle or USB sticks
That meant that two usb used plus the three I wanted on the chase meant I needet five USBs, but only had four - So web search again where I found a 4 port USB HUB with power supply.

When I had all the parts assembly and testing began... I quickly relaized that the two Western Digital 160 Gb hdds I had chossen to begin with was pulling to much power and therefor only one hdd was able to run at best if I loaded both. After digging in my PC part I found 2 old 120 GB SSD that dint pull as much power and I tested them in the rig and succes they work first time and both runnig stabel.

UPDATE January 15 2021
The 3 PSUs that where use to run the PiNAS has ben replaced with a single PSU (a ZHITING DC-ATX-160W 12V Pico Switch PSU) powered by a power brick (a HNITPWR 12V 10A 120W DC Power Supply).
A On/Off switch button to power on the PSU (24 Pin Female ATX PSU Power Supply Starter Tester Start Up Jumper ON OFF Switch
and a IDE Molex power (30cm PC Internal 5V 2-Pin IDE Molex To USB 2.0 Type A Female Power Adapter Cable) to USB with a very short USB to Micro USB to Power the Pi.