Variation Swatches for WooCommerce – too many variations

Since price depends on the size, and there are four sizes, you will just need four variations:

  1. Any Top Material, Any Bottom Material, L
  2. Any Top Material, Any Bottom Material, M
  3. Any Top Material, Any Bottom Material, S
  4. Any Top Material, Any Bottom Material, XL

This will let you select any combination of material and change the price depending on the size selected.