I installed thin "basement" carpeting on the inside walls of the cases for my road drums. Easy to cut to fit, has a spongy backing and can be either spray glued to the inside or just put around the circumference and on the top and bottom if you like. For mine I used a foam pad cut to size on the top and bottom. Plenty of room with a 1" pad for top and bottom since there is enough overlap with the lid and sufficient strap length to handle it. If you have a Jo-Anne Fabrics, Michael's or A.C Moore craft stores near you they sell different thickness foam squares and rolls that you can cut to size. Works like a champ !Michael

I used to use large beach towels in my old hard cases. i'd drape the towel evenly over the open case and insert the drum. Fold the ends over once in the case and put the cover on.