I used to think that it was impossible to print a usable normal-sized click pen structure through a 3D printer.
Bambu printer with a 0.2mm nozzle, and its accuracy is indeed a bit surprising to me.

我曾经觉得使用3D打印机实现一个正常大小的按压式圆珠笔的结构，这是不可能的。拓竹配0.2mm的喷嘴，这个精度确实有点让我惊讶!

As a 3D printing enthusiast, it's cool to have a nice 3D printed ballpen. This is a pure 3D printed retractable ballpen, with a lovely rounded shape.

The printing accuracy is key to the mechanism of the click pen. So it should use a 0.2mm nozzle, and with 0.1mm Layer height. Two plates are suggested for better quality.

It uses Uniball UMR-85N / UMR-83N as refill. and it only need a common (0.4*5*21) spring for ball pen.

按压式圆珠笔的机械结构，曾使我非常着迷。作为一个3D打印的爱好者，如果有一只这样的3D打印圆珠笔，应该是一件很酷的事。

这支笔有着圆滚滚，胖墩墩的可爱外形，长度只有12厘米，比普通的圆珠笔还短将近3厘米，携带也很方便。

打印精度是按压式圆珠笔能否丝滑的关键，所以这里要使用0.2mm的喷嘴，层高设置为0.1mm。建议零件和外壳分别使用两块板布局以提高质量。

笔芯使用三菱Uniball UMR-85N/UMR-83N。只需要一个0.4*5*21的圆珠笔弹簧。

To make it more special, with Bambu studio text shape function, you can easily customize your name or any text to be engraved on your pen. It can be printed well using a 0.2mm nozzle.

为了让这支笔更加特别，使用拓竹切片软件的文字功能，你可以很方便的在笔夹或笔身上定制文字，例如你的名字或送给朋友的祝福短语。使用0.2mm的喷头，可以很好地打印出这些细节。

Assemble details in English, pls refer to:  https://youtu.be/bVQpvxSBjMw