The original design (https://www.thingiverse.com/thing:5322891/) has the arms tilting up, I rotated the clip part down 10 degrees so the support arm is parallel to the cricut's platform.
Extendable Design allows better support for a 24 inch mat.
The design is also small enough to fit in the storage inside the cricut.
Used a #4 5/8 inch screw to secure the inner sliding part to the outer part.
The author remixed this model.