I have seen a lot of hacked together solutions for building a SuperNote DIY pen, but wanted something a bit more purpose-built. I made this a little longer than necessary so it would potentially fit other pens - you can trim it to size. You'll probably need to drill out the interior elephant's foot in the hole, so the SuperNote refill will fit.
Follow the instructions at Ratta's website (https://support.supernote.com/en_US/hardware-repair/how-to-safely-make-a-diy-supernote-pen) to adjust your refill (including trimming if necessary). I had to trim mine to fit the Lamy Safari.
It could probably be thicker, but I wanted it to be compatible with other pens, and it already fits nicely inside the top part of the Lamy so the SuperNote refill doesn't move laterally inside too much. I included my rough sketch of the design with measurements, so if you wanted to remix it for another pen you have a place to start.
LamySafari_Supernote_v3.stl | 183.3KB |