The main function of the zero-clearance insert is to prevent tear-out on the bottom edge of the piece . Especially in plywood the bottom edge will be ripped in crosscuts. CAD drawings and a 3d model are available in the CAD drawings page.
I used 12 mm birch plywood for the insert. The depth of the pockets should be checked by everyone according to the dimensions of they Bosch saws. In my version the thickness of the insert is 10,6 millimeters on the pocket locations. The pocket depths are naturally related with the thickness of the material, unless the entire piece will be machined exactly to 12 mm thickness.
A narrow slot in the middle of the insert is for a blade knife located after the blade. The zero clearance feature will be achieved when the slot will be extended by using the table saw blade. Without the knife slot in the insert the blade cannot be raised up.
Some kind of locking system will be needed if the insert is moving on its position on the saw. The original insert is locked by a spring which prevents the insert from moving while the machine is operated.
I did use small screws on the back side of the insert to prevent it lift up. The original insert contains two cast pins there.