Starting on the new kits, huh? Short of fabricating your own out of sheet brass, you are Sierra Oscar Lima. Measure the louvers on the kit, draw the louvers on a sheet of brass, carefully scribe the lines (where the openings will be) until you cut through the brass, use a pick, or some other instrument to open up and shape the opening. You could also splurge and get a photo etch making set and make your own that way. Good thing you got that mojo working, man.