2 wooden planks of any type
2 sticks
1 stone slab
Open a crafting table
Place 1 wooden plank in the top-left slot
Place 1 stick in the top-middle slot
Place 1 wooden plank in the top-right slot
Place 1 stone slab in the middle-center slot
Place 1 stick in the bottom-middle slot
Collect the grindstone from the result slot