Summary

mini-centrifuge (tabletop) for 6x reaction tubes using cheap parts (i.e. things I had lying around).

Instructions

I always wanted to have a small centrifuge for home use.

you will need:
1x graupner speed 400 motor (or similar sized motor, available at your local model shop)
1x 220V switch
1x 220V to 6V trafo (I used a small print-trafo 6V, 3.2 VA, size 35x42x30 mm)
1x bridge rectifier
1x poti suitable to regulate your motor speed (depends on your motor's ohm)
2x 3mm screws (about 5mm long)
2x 3mm threaded rod (about 1cm long), with a slit sawed into it (cheap replacement for a headless screw)
2x 3mm nut
...and an electric cord and basic soldering skills to go with it

wire the whole thing up and let the thing turn! (preferably inside a steel pot for the first test runs)

according to the manufacturers specs, the motor does 16.4 k rpm at 7.2 V (I'm running it at 6V). A first test (10 minutes at full rpm, fully loaded with 6 water-filles 1.5 ml reaction tubes) worked out fine.

printed in PLA, 1,2mm wall-size, 50% infill for all parts.
0.2 mm slicing using cura & an ultimaker

WARNING: if the rotor is not printed carefully, it may break during centrifugation and cause harm! BE CAREFUL. So far the thing works fine for me, but I was quite pedantic during the printing process and threw out multiple so-so attempts.
ROTORS TURNING AT HIGH RPM's ARE DANGEROUS!!!!

EDIT:
the rotor and casing bottom can be printed without support material. The casing top does need it.

el-cheapo tabletop minifuge