I have had this Delta dado insert for a number of years...I have used it numerous times over the years and just assumed it was an MDF core with laminate on both sides. But, now in looking at it closer I don't think it is MDF._It appears to be some sort of wood although it's heavy for it's size.I was going to use it as a pattern to make a zero-clearance insert or two out of MDF sandwiched by plastic laminate, but now I wonder if there's something better to use for the core?