Hey there, pupenaa. I'm glad to hear that you are learning to draw with a lighter grip - it has many benefits including physical strain reduction! Congratulations on finishing your box challenge, you've put a lot of great work in so let's get to it.

So you start off with already a pretty good understanding of how these boxes should be drawn, and as you progress your grasp of form and three dimensional space only gets better. You have correctly applied your extension lines and have grown from those as well so good job there. One point I would like to bring up is your line weight - I see you are applying weight around the silhouette, as you should, but your lines get a bit shaky. Remember that you shouldn't be tracing lines but rather redrawing them like the super imposed line exercise so work on those in your warm ups as line weight is one of the most powerful tools we leverage in these lessons. For the most part your converging lines are pretty good, but there are still some "back" lines that skew off on their own direction. That is ok though, because uncomfortable has made this infographic to further elaborate on how to visualize and approach parallel lines in perspective. Whenever drawing parallel lines in perspective we must be aware that they are all related to one another by the vanishing point they share. As shown in the graphic, as the vanishing point moves further away the angles between the lines decrease until they eventually become "parallel ish." So the main thing to take away from this is as we draw our lines we must keep in mind all the other parallel lines simultaneously. For example, often times beginners will drawa a box plane by plane with only that plane in mind while drawing. So as you finish one plane and begin the next, the student doesn't consider the implications of the convergences of the first plane and draws the second in a vacuum. This often results in two points of convergence rather than one. It takes some practice to be able to "step back" like this, but in time you'll get it.

I have no other comments on your boxes, you did a good job and have served your time in the box mines, congratulations!