This is a zero clearance insert for the Hercules (Harbor Freight) 12 in. Dual-Bevel Sliding Compound Miter Saw. 

I have a Prusa MK3.5 printer which cannot print this insert in one piece. I separated this into 2 parts. Each will fit (diagonally) on my printer. 

Take out the original insert and reuse the same screws to attach this insert. They overlap as shown in the picture. The rear insert overlaps and holds down the front insert.

I used PETG with 4 perimeters.