If you put 9 diamonds in a crafting table as if you are going to make a block and then use the new bundle tool and right click the diamonds (all 9) the diamond block that you were crafting is still there. You can then click on it and get it as normal and you now have 18 diamonds instead of the 9 diamonds that went in. You can do this when you turn a block into 9 pieces too by putting the block in the bundle but still taking the block and still getting the 9 pieces. You can do this with netherite too.