Build Quality

Overall build quality is very solid. There is no rattle when shaking the mouse. When applying lateral pressure, no creaking or flexing of the shell can be observed. Activating the side buttons by squeezing the sides is impossible. Lastly, accidental clicks when slamming down the mouse do not occur, provided the slam-click filter is enabled.

Buttons

Main buttons on the OP1 8K are very good. The left button has low pre and moderate post-travel, whereas the right one has moderate pre and post-travel, resulting in a very firm and snappy button response. Despite being visually separated from the shell, button movement is minimal even when provoked. Button stiffness is medium. A pair of Kailh GX (80 M) switches are used.


Side buttons are excellent. Both pre and post-travel are low, leading to pleasant actuation, and the pressure point is perfectly across the entirety of these. Button size and placement are quite good, as actuation is possible rather easily by rolling one's thumb across. A set of Kailh GM 2.0 switches (black plunger) are used for these.

At the bottom of the mouse is a single button for cycling through the set CPI levels, which works fine. A seemingly unbranded tactile switch is used here.

Scroll Wheel

The scroll wheel is very good. Noise levels are somewhat elevated, but tactility is great, with clearly defined steps allowing for controlled scrolling. The encoder comes from TTC (white or "silver") and has a height of 9 mm. The middle (scroll wheel) click requires high force for actuation. Another Kailh GM 2.0 switch (black plunger) is used for this one.

Surface

The OP1 8K has a matte surface all over. Grip is fine, but it does attract fingerprints and dirt to an above average degree. That said, it is fairly easy to clean, and there are barely any signs of wear left after doing so. All in all, good materials.

Button Sound Test

Disassembly

Disassembling the OP1 8K is trivial. The two screws are readily exposed, and after removing them, top and bottom shell can be separated with ease. When separating the top and bottom shell, make sure not to rip the cables going to the top shell.

The internal design is highly efficient. The main and side buttons sit on their own PCBs screwed into the top shell, the former connected through a 3-pin connector and the latter through a 4-pin connector to the main PCB. All PCBs are very thin, and the very compact main PCB has been affixed to the bottom with three screws. The MCU is a Nuvoton M483SIDAE, whose datasheet can be found here.


As for the soldering and general quality of the PCB, I'm unable to find any noteworthy flaws.