I made a bolt action pen that uses fisher refills，This is also a fidget toy.You need a 3X12mm pin and a 0.6x8x40mm spring, available from the Bambulab store.

Only four parts, no support required.

我制作了一个枪栓战术笔，使用fisher太空笔芯。需要一根3X12mm的销和一根0.6x8x40mm的弹簧，拓竹创客宝库有售。仅有四个零件，无需支撑。