Inside the PC-Q27 B
After removing one screw on each side, you lift the panels out of the grooves in the frame of the chassis. On the back of the panel you can see four tabs that lock into the frame. Inside of the chassis you can see the hardware strapped to the back as well as the moisture absorbing paper and front I/O wiring.
This is the removable 5.25" drive rack. It is held in with four screws, and makes installing an optical drive easy if you plan to hang a hard drive from the bottom of it.
The front inside wall of the chassis is left in its natural state, and you can see the back of the power button and LED system at the top of it. The rest of the panel has these key slots, eight in total. One set of four will allow you to install a 2.5" drive here, or a 3.5" hard drive, but only either or.
The motherboard tray, if you will, is actually a pair of flat sections that run left to right. They are pretty thick, already have the standoffs in place for a Mini-ITX motherboard, and will allow the back of the motherboard to stay cool.
The floor of the chassis has a pair of brackets installed that will allow you to install a 3.5" drive between them. If you would rather, you can remove them to install a fan, or a 2.5" drive in the slots between the brackets.
The back of the chassis offers a removable plate that will easily install on the back of the power supply. Once combined, you can replace the plate and PSU into the chassis, right in front of the motherboard. Choose wisely with coolers, there is very little room for anything normal to cool the CPU in here.
Much closer to the floor, you can see the single expansion slot and its ventilated cover. Removal of the cover and securing a card is done outside the chassis since the slot is slid all the way to the back plane of the chassis.
Looking at things from behind the motherboard support bars, you can see that there is only maybe 2mm of space before you hit the side panel, so any dreams of wire management magic here are not going to happen.
Connectivity of the chassis to the motherboard is kept very simple. There is the Native USB 3.0 plug on the left, the power LED, power switch and HDD LED on the right, all of them black as well.