(Note: Old, delete this)

craftingTable.addShaped("minecraft_slime_ball", <item:minecraft:slime_ball>, [
    [<item:minecraft:warped_wart_block>, <item:minecraft:warped_wart_block>, <item:minecraft:warped_wart_block>], 
    [<item:minecraft:warped_wart_block>, <item:minecraft:warped_fungus>, <item:minecraft:warped_wart_block>], 
    [<item:minecraft:warped_wart_block>, <item:minecraft:warped_wart_block>, <item:minecraft:warped_wart_block>]]);