I want something very simple that will be able to hold any size of pen or maybe some kind of other tool too.

The best way is to start with the original part shape (base of the extruder). From there, I just extruded a large tube at the center in which I made 3 pairs of holes where 6 screws will take place. That way I will be able to fit a pen of any size that will be easily removable (size and/or color change) and will also let me hold my pen in a diagonal position if needed.
And this kind of design can be easily printed without the need of support.

Here is the part ready for printing :

Pen holder

And here it is printed :

Tool holder

For my first test, I simply fixed a bic ball pen in place using the 6 screws.
The drawing started nicely but very soon the paper began to warp and get torned because my bed isn't perfectly flat and/or leveled. So in some places the pen just get crushed on the bed with too much pressure.
I checked my bed levelling but it was OK. So the reason is that my original acrylic bed is not perfectly flat anymore. As I allways 3D print in the center of the bed, it became slighltly concave in time, and is lower in that place than at its borders.
To fix that, I have 2 possibilities :

  • making a new flat bed
  • mount the pen on a spring (shock absorber)

I decided to make them both...
For the new bed, I simply used the original one as a template and cut it out from some PCB. I also decided to replace the original acrilyc framed base bed (part #10020) with PCB in the same time.
To have my pen mounted with some shock absorber, I fixed a small aluminum tube using the 6 screws. The pen can now freely move up and down in the tube (and can be easily changed while keeping a good position precision). A rubber band will push it down in the tube providing pressure and shock absorption property. But I will also need a way to prevent the pen from going down too much. Because when it will have to be raised up, it musn't touch the bed/paper anymore (travelling without drawing).

In Sketchup, I designed that part that will take place under the previous one in replacement of part #10035 :

Pen holder (bottom)

But as I'm a lazy guy, I decided to look around for an alternative before going printing. And I found out that the top of a soda bottle could do the job. Even better : I can have several caps (I keep several ones with different colors) for different hole diameters.

Here is my final mounting (don't remove part #10035 if you use the soda bottle method) :

Pen plotter (parts)Pen plotter (mounted)

And now I have no more "paper jamming" !

2D plotter