This is a self-sprung pen holder, remixed from here. The point of the remix is to make an OpenSCAD file that lets you increase the width and depth (changing the height will affect springiness) to fit deeper pens, and still keep round (and now adjustable) screw and nut holes.
The default settings are now for a maximum 15mm diameter pen.
This mounts to the cutting/printing head with two screws with centers spaced 20 mm apart. (The spacing doesn't change as you rescale.) You can alternately produce mounting bumps if you are gluing it into a platform that has appropriate holes. (Here's my platform for the Da Vinci 1.0a.)
XYZ DaVinci 1.0a with Repetier
Used a brim to prevent warping.
The 120% size version fits a 15mm fabric marker too snugly (the nut scratches the screw). A touch with a sanding drum might be in order.
I converted the original STL to SCAD using a python script I have here. (You need both stl2scad.py and stl2svg.py for it to work.) I looked where the original holes were with Meshlab, then wrote a bit of SCAD code to fill them in and draw new ones.