This is a pen holder for three Pentel EnerGel pens, https://www.pentel.com/products/energel-rtx-gel-pen
It can be 3D Printed, or it can be milled on a CNC with a ¼ ball nose endmill, solid hardwood mills well into it, but it can be theoretically produced with few limitations.
The author marked this model as their own original creation.