I model this ergonomic stylish modern pen to fit the gel pen refills that I like the most. It's the Penel EnerGel. If you like writing, you should give it a try. I'm sure you will enjoy the smoothness of the ink which glides on the paper while you write.

The dimensions of this pen is precisely adjusted to ensure all components fit together well. The refill stays stable while you're writing. No wobbling feel ! To achieve this, it took me quite a while to fine tuning the dimensions and print profile settings, and of course with many trial runs. I use the color of the “latch” and the little bee symbol at the end of the pen to identify the color of the refill installed in the pen. 😉

Pen Refills can fit into this design:

• Penel EnerGel
• Uni-ball Signo

Both needle or classic tips will work.

Springs:

The springs from the old disposable retractable Penel and Uni-ball pens work great. 

This model can use springs meet the below specifications.

• length 21 - 26 mm
• outer diameter 4.5 - 5.0 mm

Shorter spring will not have enough retracting force. Longer spring will be fully compressed to its solid height and prevent the “latch” from locking in it correct position when extend the pen refill.  If you cannot find any old pens, you can use the springs selling in Bambu Lab website in Maker's Supply. I've put the link in below for the correct size of spring.

Printing Material and Profile:

Both print profiles have been fine tuned after many trials to yield the best result. Do not change the setting unless you know the slicer settings very well. Make sure filament is dried enough to prevent ugly surfaces or brittle prints.

• PLA - Very easy to print. Supports and brim can easily be removed from the parts.
• PETG - A bit challenging material. I strongly recommend you to use dried filament. Supports and brims can stick too well on print bed. Also, the print profile based on Bambu Lab PETG-HF.

When remove the parts from print bed, please handle the “Cap” gently.  It has a very thin wall. If you hold it tight to force remove it from print bed, you can crack the thin wall.

Ignore Warning Message:

If you see this floating warning message when using Bambu Studio, you can ignore it. There is an overhang area inside the cap which doesn't matter. Don't put support as it will affect the function of threads.

Before Assembling:

1. The refill exit hole on the pen is designed to have slip fit to ensure no wobbling while writing. Please use the metal tip of a refill to clear the hole until sliding smoothly before assembling.

2. Fully remove residue left from the brim removal from the pen barrel end.  If any brim material left on the edge of barrel, they can act as a knife to cut the thin wall of the cap when they assembled together. 

Assembling:

There are only 3 printed components which can be put together in a breeze as shown in the video.

Assemble the “latch” in direction shown in the photo below:

My Failed Prints:

I've lots of failed trials, so I don't want you to repeat them. Please use the print profile for good results. 😉

Finally… hope you will love this stylish modern retractable pen design. It's a good gift for people who enjoys writing.