Have you tried brital vail? The netting that I have used for this project has large holes and these allow the Colt cuttings to extend individual polyps above the netting. By folding the netting into triangles we are able to cut a large number of small circles at once. You start making the circles by first folding the netting into a small square that has several layers. The circles of netting should be just large enough to cover the top of the rubble and allow a rubber band or glue to hold the netting in place.
Use our stainless steel tweezers to pick up each cutting and place it on rubble. When we are placing the cuttings we try to position that so that the stalk is against the top of the rubble. This allows the polyps to extend through in the netting. After several polyps have expanded outside of the netting you can be certain that the cutting is secure.
I have used rubber bands or super glue gel to secure the netting over the cuttings. The netting should be pulled down tightly because the cutting can shrink and it may work itself loose if the netting is not tight enough. The fresh cuttings should be placed in the part of the tank that has very strong water movement.