The Siphon II pen by Microtech to give you the utmost strength in the design. It is classy, easy to carry. The retractable tip is activated by the lever. I reproduced this classic design and enlarged the volume appropriately to make it easier to 3D print with a better structure. Please use a lower speed and layer height to ensure the overall structural strength and thread precision.This is a fun thing, I hope you like it.

This pen uses a Fisher Space Pen SPR pressurised refill.You need a 3X12mm pin and a 0.6X10X50mm spring（The pin can also be replaced with a printed part, and the spring can also be replaced with a similar specification with a diameter of 8-11.5mm and a length of 40-60mm）.