A centrifuge is EXTREMELY DANGEROUS, do not use these files to make one. These files should only be used for information purposes.
I am too cheap to buy a microfuge so I designed this rotor to attach to my RC motor. The mounting hole is .25" diameter and was designed to fit an exceed-rc rocket series 86MA08 brushless motor. The tube angle is 55deg and the rotor holds eight 1.5ml microtubes. This part was designed in Geometric Design (formally Alibre Design). The original file can be altered to accept larger or smaller shaft sizes.
Revision 1: Changed angle to 55deg
Print with flat side down on high res and you shouldn't need support. The STL has been exported in mm but the part was designed in inches.