Nice job with finishing the challenge!

Some feedback on your work, there are several instances where you extend your lines in the wrong direction, 178, 213, 248 are all some examples. You need to extend the lines away from the viewer, and out into space, these boxes are extended outward towards the camera. When you plot your box's lines you need to think about where the lines are traveling in space.

232, also has the same issue but it's a bit harder to tell, when you can only see two planes of a box because of the angle that you see it, you still need to consider which of the obscured planes is closer to the viewer, the thinner looking plane will always be closer as explained here.