This design is a handle for small drill bits. It is a remix from my blade handle (https://www.thingiverse.com/thing:6805463) and also uses a mandrel system to securely hold the drill.
To build it you need a 25mm M3 screw and a melt insert. Print one "handle", one "Knob" and choose one of the mandrel types. The mandrels are characterized by two numbers. The number following "D" is the diameter of the drill bit and the number following "I" is the diameter of the melt insert. The mandrels can accommodate drill bits with diameters of about -0.4 to +0.1mm.