You have to remove the four thumbscrews holding each glass side panel in place to access the interior. Once released, flip them down to pull them away from the metal frame. Everything inside the Cougar Panzer is black, with the large orange brand logo quite prominently placed on the shroud. The layout is quite simple as there are no traditional drive bays - not even for internal storage units. Instead, Cougar has chosen to make the space available for either air or liquid cooling. There are some drive trays on the backside of the motherboard tray, with a fairly large opening to allow for access to the CPU cooler's backplate.
The motherboard tray itself allows for 16 mm of space - which is not a lot, but enough to route more compact cables - while the front part of the chassis clocks in at 35 mm. Odds are, this is where you secure most of the larger leads.
Cougar has basically left enough room in those areas to allow for the right type of drives to be installed. You will find two 3.5" HDD mounting trays in the front, where there is more space, while the two 2.5" drive variants have been placed on the motherboard tray itself as you have about 20 mm less headroom here.
Looking at the front, you can see that the entire space there is intended for cooling. There is a large opening in the shroud, which means you can use the full height of the chassis here for the largest-possible radiators. While this opening is great, it is a bit too large. Instead, Cougar could have made it a bit more compact and added an additional 2.5" hard-drive plate here, or placed cutouts to mount a pump onto the regained surface area. Talking about hard drives: You will find two mounting trays for SSDs on top of the shroud, which brings the total number for such storage units within the Cougar Panzer to four.
In the rear, starting underneath the shroud, the PSU bay itself is pretty standard with its rubber mounts on which the power supply will rest once pushed into the chassis. Above that are the aforementioned expansion slots for the motherboard. As you can see, there is a metal plate holding all seven of these in place, but they do come with individual screws to make sure things won't fall apart as soon as you remove the plate. The exhaust fan in the very top is quite standard, being all black and having the usual seven blades and OEM-colored cables. It would have been nice to see a more intricate unit, or even a second unit in the front.
Looking at the top, things are quite simple from this angle as well since all the space is for cooling. You can see the green PCB for the upward-facing I/O in the above image as well.
All the cables within the Cougar Panzer are of the default variety and are sleeved black to go well with the interior paint job. No surprises here, so let's keep on moving.