I had been looking for an EDC Pen to print that could use my preferred refill, the Pentel Energel Liquid in 1.0. These are A$1.88 bought local and write better than the A$13 Lamy refill I used previously. I printed this one and found that if I cut off 16.4mm of the Energel plastic refill, which is below the ink line, it works a treat. Unfortunatly the lid in the original design was just a hollow tube. So I created a cap stopper and pen clip to go in it. I used a drop of cyanoacrylate (super glue) to hold it in the tube cap. Most roller ball refills will either fit in this pen or could be easily modded to fit as the original designer used a printed grub screw configuration to adust for then length of the refill. No other hardware is required for this pen outside of the drop of glue for the cap stopper/clip and the refill of your choice.