A microswitch located near the cover cuts the power when the cover opens, and returns power to the motor when it is closed. It is a common safety feature found on many laboratory micro centrifuges.
Because it is much simpler and because there is a lot of extra space in the housing, a lot of expanded functions can be added later by users. While this version does not require a microcontroller of any king, there is plenty of space to add one (for timers or other functions).
Check out all the files here on Thingiverse: https://www.thingiverse.com/thing:2598206
Check out a quick video demonstration here:
For information on a simple DNA extraction protocol we've used in the past which utilizes a micro centrifuge, see here.
