About this 3D model

The pens I use are Uni Pin brand, so if they are another brand I have no guarantee they'll fit. To see if your pens would fit (as also other printers may have different results in fit) first try the small test print part, which should have a strong fit. I wanted a strong fit as if its too strong I could always sand the inside a bit, and there is a small hole at the bottom to help get it out if its really stuck. For reference; the inside is 11.1 mm in diameter, and a small bit at the end is 9.2mm in diameter.