Hi and a glow thread is a great idea. I think there is one here that I remember reading and asking questions on... But a fresh one for our research sounds smart! I bought the reusable pen set from Research Roi, comes with some pen needles, cartridges, bought some extra cartridges and a cartridge stand, all from them. It's on its way to me now. Should have it by the weekend, though I won't do anything with it till I reconstitute the vials for the Glow. If I recall correctly, the cartridges are 3ML, so I have to remember that when reconstituting. Research Roi has also just put up a video about how to load it etc which was very helpful and I downloaded it. I think it's one of those things that seems very complicated until you do it. If it is easy enough to do and I like using it, I'd probably invest in another one for tirz. The cartridges are full and use and discard. You can switch out cartridges in the same pen. The case has a place to hold a filled cartridge though I was reminded to mark it! Bought it though I have a ton of syringe/needles!