Make a cheap mans Ginko Cloud. Just get a maple cutting board of an appropriate size. Then buy a bunch of squash balls on Amazon or at your local sports store (if they carry them). Place them judiciously with more under heavy parts of the shelf and less under lighter areas. They will flatten a bit over time and not roll around, like a racquetball would.
Woked like a charm for me.
Woked like a charm for me.