I really like this design myself: Simple Centrifuge ...putting a centrifuge in every garage!
If you watch one of the videos, there's a blueprint/cutaway view of it; you could easily whip up some actual blueprints with that and measuring the picture(Hint: the overall stock size used for that appears to be 9" diameter)
I'm intending to do this myself one of these days, but I've got to get some 9" aluminum cyl myself.
From there website:
If you REALLY want to build your own centrifuge,this is the key piece: Includes:
-Seal and clamp
-Parts list for centrifuge
Includes: -Machined Rotor, -Clamp Bushing for 5/8" Dia motor shaft (no key), 5/8" Shaft Collar, 5/8" Dia Viton shaft seal.
Instructions to build an enclosure and basic layout are available here: Download Designs