There'll be a new, small button besides your "Shop" interface where you buy towers and items in the game that reads "Crafting". Once you click this button, you'll go to the Crafting Table interface and the game will pause. Once in the Crafting Table, you can click the Recipes button, click one of your recipes to select it (recipes can be gotten by doing things such as use x item y times, pop x bloons of y type, reach Rank n, complete mission z, etc...) Then you'll drag the necessary ingredients from the Inventory to each point of the Star of David, and adjust their quantities. Each point of the star is for one type of ingredients only, so the craftable items with the most types of ingredients should only have 6 types of ingredients. When you're done, click the circle in the center and you