All you need is a level 3 lumberjack, a level 2 workshop, a level 2 stonecutter and a level 1 paddock to make 30 planks. In order to make a plank you need one stone tool. A stone tool is created by 1 set of stone blocks and 1 set of lumber. Stone blocks are created by using stone (which is a reaction you can create for free) and 1 piece of meat from the paddock.