What do you define as “building”?
With all my x86 desktops since whenever the Athlon “Thunderbird” came out, which was … yeah … 2000, I’ve “build” them myself, defined as: pick a CPU, ATX motherboard with the same socket, RAM to fit the MB, disk with appropriate IDE/SATA/M.2 interface to suit the motherboard, case, power supply … and plugged it all together. A process taking an hour maybe.
In 1983 two friends and I built a 6809 computer by buying a 6809, some RAM chips, a ROM chip, some TTL logic chips, and we figured out which pins to connect to which pins and we wire-wrapped the whole thing. I was particularly proud of the clock circuit I designed which ran at 1 MHz while accessing the UART, at 2 MHz while accessing the RAM, and at 1,33 MHz (500 ns high, 250 ns low) when accessing the ROM as I noticed that although it was spec’d as 1 MHz it was only actually one half of the cycle that was critical.
We also wrote our own OS and compiler back end (from BCPL ocode).
There is quite a difference between the two versions of “building a computer”!