2 point perspective is only slightly harder than one point perspective and uses 2 vanishing points, one of the main things you have to watch out for is how close together the vanishing points are as this could change the shape of your object and for a cube could lead to it having more of a diamond shape than a square shape if they are too close together or too far apart, you could think of it as if they are too close together then they will squish the object if they are too far apart they will stretch it. But that being said you could place the vanishing points closer together or further apart to create effects in your drawings.
Below I will demonstrate how to use 2 point perspective to draw a cube if you have already looked at my earlier post on 1 point perspective a lot of this will be familiar to you if not I recommend you take a look.
This first image is of the initial stages of drawing the cube with the horizon line (in blue), the vanishing points (in green) and the lines of the perspective grid (in grey), also as I begin to add the cube that will be drawn in red. Even with only a few lines added you can already see the base of the cube starting to appear created by the intersecting perspective lines.
Here I have added the red lines for the base of the cube following the square that was made by the intersecting perspective lines. If you want a larger cube all that you need to do is space the perspective lines further apart.
Next you want to add a line from the front edge of the base of the cube, this will determine the height of the cube and from the top of this line add two perspective lines to the vanishing points as shown. It is from these lines that you will create the top of the cube in the same way the base of the cube was created.
With the last 2 perspective lines added you can start to see the shape of the cube. At this point you can add the line at the back of the cube from the base to the intersection of the perspective lines marking the top if you are drawing a cube that you can see through, but if that is not the case it can be left out.
For those attempting this on traditional media such as pencil and paper when drawing perspective lines draw them as lightly as possible this means that they will not have to be erased at the end and you don’t risk removing something you wanted to keep. For those drawing digitally remember to use layers to separate the perspective grid from your cube.