I have always used an alder plank. I was given a few by a friend, so I never made my self. I feel that it would be easy enough to get a 1 1/2' alder rounds (dry) and split them in into 1 inch thick slabs 8" wide. I put the plank on the bottom grill of the barbie with the fish skin side down on the plank. The grill will start to burn the plank which gives the fish a nice smokie flavor. The plank also seems to sweeten the filet by the direct contact with the skin. It is a great way to do the fish. Enjoy.