A Closer Look - Outside
Taking a first look at the chassis, the design is quite well done, with the top, front, and bottom panel having been made out of a single piece of fairly thick aluminum. While the chassis is clearly pitted against Lian Li, the U3's unique size and form factor have no equivalent by Lian Li. The individual panels on the Cooltek U3 also feel to be of higher quality than those of a Lian Li chassis, as they seem thicker.
There is no external drive bay on the Cooltek U3, which is the main reason behind its ability to hold mATX boards despite its tiny size. We can see Cooltek taking a traditional approach in the rear, with the separate areas alined much like that of a mATX tower. Both side panels are completely solid, but come with compact air vents toward the front of the chassis.
Considering the fact that there is no Cooltek logo anywhere on the chassis, I would not be surprised to see the chassis used by various system integrators who put their own brand on the chassis exterior. The front I/O consists of two USB 3.0 connectors and the usual pair of audio I/O. The only other element on the front is the circular power button, with a ring-shaped power LED around it.
The bottom part of the rear is taken up by four motherboard-expansion slots. Each individual cover is held in place by a thumbscrew. Above that is a fine grill behind which is the only exhaust fan—a 120 mm fan pushing air out the back of the case. If you look closely, you will see a little speed-adjustment switch below the fan. Your two choices are "high" and "low". In the very top is a simple PSU bay with a single set of screws. You will then install any power supply with the fan facing downward, which helps in cooling any internal components.
Tipping the Cooltek U3 on its side reveals the hard-drive bays on the floor of the chassis. You may install a single 3.5" drive here out of the box, but Cooltek also includes all the parts to switch things over to two SSDs, for example.