You can build in this case pretty easily as long as you don't try to do fancy things, like custom loop. It's smaller than the Corsair One, and you get better upgrability. It's small and discreet. Silent depends on what parts you pick.

There are many other cases that are similar, but not quite as space-optimized. Popular ones include the Ghost S1, and the Ncase M1. All three support the same-caliber specs you would get with a Corsair One.

Let me know if you want help selecting parts/building in such a case.