Philosopher's Stone

Right-click a block to transmute it: stone↔cobble, dirt↔grass, gravel↔sandstone, water→ice,
lava→obsidian, melon↔pumpkin, cycle woods, leaves, saplings, planks and wool colors.
Sneak = other direction.

Sneak + right-click air: size 1×1 → 3×3 → 5×5.
F (swap hands): shape panel → line → cube.
Right-click air: portable crafting table.

The stone stays in the crafting grid: 4 coal → Alchemical Coal, 8 iron → 1 gold,
4 gold → 1 diamond, 2 diamonds → 1 emerald (and back). With coal + 7 raw ores it smelts like a furnace.