diy styrofoam no sewing avalon cornice kit 12 inch drop diy cornice kits the avalon cornice is offered in 6", 9", 12", and 15" drop/height. the 12" avalon cornice looks great on standard size windows and over sliding glass doors.<br><br> determine what drop looks best by using an 81⁄2” x 11” sheet of paper. hold the paper landscape where the cornice will be installed. this simulates the 9" drop cornice. if it’s too big, you'll want the 6" cornice. rotate the paper so that it's portrait; this simulates our 12" cornice. if it’s too big, order our 9" cornice. if it’s just right, you'll want our 12" cornice. if it’s too small, then order our 15" cornice.<br><br> our 491⁄2” starter kit contains 3 161⁄2” extension pieces, 2 end caps, 1 tuck tool, mounting hardware, and instructions.<br><br> if the starter kit is not long enough, order more extension kits by clicking the extension kit variation above.<br><br> you may need to shorten one extension piece; here’s how:<br><br> cut the piece with a drywall saw, hack saw, electric knife, or utility knife. stand the piece that you’ll be using upright on the smooth end, so that the rough end is on top, and cover it with aluminum foil. using a heated electric iron, pat the aluminum foil to melt the styrofoam flat and smooth.<br><br> let us cut your cornice to length for you, in the customization section of this listing, and tell us how long to cut it.<br><br> 5" brackets and end caps are provided with our kits. this means there is 5" of clearance between the wall and the back of the cornice. you can substitute 3" brackets to move your cornice closer to the wall. you may need custom brackets for your cornice. we have made them as short as 1⁄8" and as long as 10", and we modify the end caps accordingly for your custom brackets. select your bracket size in the customization section, and let us know your custom bracket size.<br><br> bay window and corner window information can be found by clicking their variation above.