Convert between sand, red sand and gravel: 3 of a block + 1 of another = 4
3 Gravel + 1 Sand (or 1 Red Sand) → 4 Gravel 3 Sand + 1 Gravel (or 1 Red Sand) → 4 Sand 3 Red Sand + 1 Sand (or 1 Gravel) → 4 Red Sand