There are many CNC pen holders out there but I wanted to create my own work on my Fusion skills so here is my take on a very useful CNC tool. 

It does require a few parts and links can be found below. 
Push the M3x12mm Hex head bolts into  the body of the thumb screw bodies. This part is slightly tricky but if you look into the main body where the pen goes you will see two spots for M3 nuts, I used the bolts from the outside, threaded them into the holes a little bit and then used my finger to get the nut in place and thread the bolt onto the nut and then use the bolt to seat the M3 Nut. They should hold themselves in place once seated. 
Start by tapping the dowel pin into the body of the bottom cap, its the round part with no through hole, the dowel should fit pretty snugly into this part. Slide the main pen holder body over the dowel pin. Now slide the spring over the dowel and it should sit between the dowel pin and the pen holder body. Put the top retaining cap on the dowel, push or tap the top retaining cap down so that the top of the cap is flush with the main pen holder body, the spring should be slightly compressed. Take the M3x6mm socket head screw and put it into the top cap and secure it with light pressure.
Slide a pen into the pen slot and tighten with the thumb screws, if the pen or pencil is thin you may need to use the thin pen wedge to help secure the pen. Pens like a Sharpie should not need the wedge. 

Parts Needed: 
2 x M3x12mm Hex Head Bolt - [https://a.co/d/01ae3m6C](https://a.co/d/01ae3m6C)
2 x M3 Hex Nuts - included in above kit

1 x M3x6mm Socket Head Bolt - Optional Part to secure dowel pin
1 x 60mm x 6mm Dowel Pin - [https://a.co/d/0hOsrjfk](https://a.co/d/0hOsrjfk)
1 x 0.6x8x20 mm Spring - [https://a.co/d/00BzqWQd](https://a.co/d/00BzqWQd) or [https://ca.store.bambulab.com/products/compression-spring?id=46333281403120](https://ca.store.bambulab.com/products/compression-spring?id=46333281403120)