Minecraft wiki entry for Creating_shapes, associated text: Equilateral triangles are a little bit more abstract than right triangles, but they still have a clear way to build them. First, build a line of blocks however long you want your triangle to be. Then, build one block up on the edges of the lines. Continue by building in sets of 2 blocks up, going 1 block inwards each time. Look at the following grids for examples: