The speedy capper itself is the device being used to cap and uncap the eppendorf tubes.

These are some concepts for the speedy capper. They are not necessarily dimensioned, but serve as conceptual models for discussion.

This design, shown as a cross consists of three concentric parts: the outer shell which is transparent, the decapitator in blue, and the decapitator in red. The decapitator moves down and wedges the cap against its inclined walls which would be lined with a rubber material. A spring then retracts the decapitator and pulls the cap up with it. The recapitator works similarly and dislodges the cap in its motion and presses it onto the eppendorf tube. Then a spring returns it to its normal state.

Here's an image with the springs in place.