I traced the shape of the OEM mounting plate onto a piece of Lexan than then cut it out with my band saw and hole saw in a drill press. I had to break off one of the 4 speaker mounting tabs to prevent interference with the speaker grill mounting slots. I used a bracket I have for mounting things into slatwall which fit into the slot in the car to hold it perfectly. Once I had the plate built, I covered it with some black vinyl so it would look good through the speaker grill.