The Boylston Collection - Set of 3 - Fusible Glass Slumping Molds Molds measures approx. 7" SQ x 1.5"H (serving plate), 10" L x 5" W x 1" H (serving tray) and 3" SQ x 1.25" H (condiment dish). We successfully use all of these molds in our studio without issue (please see the additional photos in this listing for completed samples). Pre-drilled holes are not required for a perfect slump. Just make sure to elevate all the molds, pre-drilled holes or not, above the kiln shelf or floor by at least 1" by using kiln posts. If you follow this procedure, you will have no problem using any of these molds. To use, simply pretreat the mold with kiln wash or nitride spray, and slump your prefused or sheet glass (cut to size) using a slumping kiln schedule. The series of photos show the Boylston Serving Collection created using our Evergreen Designer Rod Set made from Bullseye Glass!