The FOCUS variation is available for all of my builds. For a Focus build, I use the rarest, most historically accurate components available. Not many builders spend the endless hours required to find this old stuff anymore (and I'm almost at my wit's end too!).
The Focus upgrade also allows you to pick the color and type of enclosure, as well as some part types and circuit voicings.
-'60s UK, Italian, and USA caps and resistors from Hunts, Iskra, Piher, Erie, etc.
-transistors from Mullard, New Market, RCA, etc. often with the correct part numbers like OC81D, OC81, OC75, OC71, OC44, 2N270, 2N261x, 2G381, 2G374, NKT-213, etc. I try to find transistors with not only the correct part numbers, but also with historically correct fonts and brand labeling.
-Real '60s Vero UK board; phenolic tag board; paxolin board; perf board; bakelite copper-clad PCB, etc.
-Correct assembly style, from the immaculately clean builds found in many Sola Sound and Hornby Skewes effects, to the charmingly sloppy work by Maestro, Baldwin-Burns, and Arbiter.