Scale it to 300% and he can hold pencils and more.

I also attaching Blender file with armature so you can change position and angles of arm.

if you know how to use Blender :)

Maybe in future I add motors and control for real movement.
 

Print settings:

Scale ~ 300%

Layer height: 0.2mm

Infill: 10% (more infill will help prevent tipping over)

Support: Everywhere (better organic support in Prusaslicer 2.6)

Raft: no