Twist Pen

thingiverse

**Twist Pen** This is a customizable (OpenSCAD) version of a 3d-printed pen design inspired by Kairi Eguchi's similar design. I first saw an original version of this pen [here](https://www.yankodesign.com/2021/07/05/this-3d-printed-pen-comes-with-a-literal-twist-that-acts-as-its-eye-catching-detail/ "Pen Article"). All concept credit is due to the original designer whose website is [here](http://kairi-eguchi.com/en/ "Designer Website"). I decided to try to design and print a replica of it and found it was really ergonomically pleasing. The twisted portion creates a nice, comfortable grip. This pen is customizable with several different twist styles and two different tip styles that can be seen in the images as well as a customized text field for a name or other text. *Twist Styles* - The reference design appeared to use a dimension consistent with the pen body throughout the shape. One drawback of that approach is that the pen can roll when laid down. The "constrained" styles in this design are intended to somewhat maintain the aesthetic of the pen while constraining the dimension of the twisted components such that the pen still has an overall *square* shape and will not roll when laid down. *Cap Styles* - The squared-tip style has a "friction feature" on two sides that is meant to help capture and hold the cap in place. This may require post-processing to file down to an appropriate size for a reasonable amount of resistance when sliding the cap on. In truth, I've had issues getting the cap to stay on. Note: In earlier versions I had a detent in the cap complementary to the friction feature in the tip, but its use tended to de-laminate the bottom layers of the cap over time. To resolve some of the cap retainment issues, I've also added a threaded cap option. This isn't quite as aesthetically pleasing to me, and may require some post-processing of the cap (i.e. filing or sanding away the bottom) to ensure it aligns with the square body of the rest of the pen when in place. At these dimensions, the side walls of the cap are pretty thin, making it difficult to enlarge the threads. Likewise, the tip won't stand up to too much torque applied through the cap before twisting off. The original designer apparently used a small magnet to hold the cap in place. I was hoping to achieve a completely printed solution (i.e. without the need for the magnet). Suggestions to improve the cap style and cap retainment of this design are welcome. *Pen Insert* - I used inexpensive BiC Cristal pens for the pen cartridge insert. This pen cartridge has an approx. 3.8mm-diameter barrel near the tip and is approx 125mm long. *Printing* - The pen body and cap can be printed in the vertical orientation. I recommend to print each in separate operations to minimize x/y motion during either print operation. I've printed with a 0.4mm nozzle at 0.2mm layer heights, with a raft. *Post Processing* - Prior to inserting the pen/ink cartridge, I ream out the tip with a 9/64" drill bit (and very slightly enlarge the hole from the 9/64 size). To clean up the bottom (of the pen) and top (of the cap) after separating from the raft, I've lightly dry sanded with 220 and wet-sanded with 600-grit sandpaper. If using the threaded tip, it might be necessary to fit test and sand off material from the bottom of the cap (i.e. the threaded end) to achieve good alignment with the pen body when snugly closed.