Hey there zexel, no worries on the messy pages, it shows you were working hard and applying the extension line method as per the instructions!

Throughout this challenge you have made great strides in your ability to draw boxes and more fundamentally, in your understanding of three dimensional space. Your convergences are much more deliberate and thought out by the end, and your boxes are much more solid. One thing that could still use some work is your overall line quality, as many of your lines still feel like they are lacking a lot of confidence as if you either were not ghosting your lines or not using your shoulder enough. Not the biggest deal in the world though, just keep practicing your line work exercises and building up that confidence.

In regard to your perspective and converging lines, you have made quite a bit of progress in getting your lines to converge more consistently throughout and while you still have a few hiccups with your back lines going askew overall you're on a very good track. To further facilitate growth, uncomfortable has made this infographic to expand on drawing parallel lines in perspective. While we are discussing this in the context of boxes remember that it can be applied to any set of parallel lines because in perspective they (the parallel lines) are always going to share a vanishing point. So what this image is describing is how the parallel lines are all related to each other by the vanishing point and the vanishing point's location is what determines the angles between said lines. To practically apply this we must "step back" from our drawings and start to view all parallel lines in concert instead of individually. Usually we draw boxes one plane at a time and don't regard our first lines when we move on to other planes resulting in multiple points of convergence instead of one. Instead we must use each line to inform us of the trajectory of the next lines. It is not an easy task to conceptualize, and takes time but with practice it becomes intuitive. So with that I have no other critiques on your boxes. You have followed all of the instructions and made strides of improvement and I will be marking your challenge as complete.