Hey there Rokas, I'll be handling your 250 box challenge critique.

First of all congratulations on completing the challenge, it's a test of willpower as much as anything so pat yourself on the back for such huge accomplishment and display of discipline.

One last quick note before going into your boxes too much is that in the future it may be beneficial for you to number each drawing in a challenge after completing them. It helps people give you critique easier since we can quickly point out the box we're talking about rather than trying to explain which box it is on the page.

So overall I'm happy to say that your boxes have improved. Around box 100 is where I notice the first jump in quality and around 150 is the second jump. At those points you start to converge more consistently and it makes the boxes themselves look more solid. Your line work has also improved and become more confident over the course of the challenge, you may want to experiment with line weight in the future, it can really help your images pop on the page. Even in things like your hatching you can see improvement in your tidiness and mindfulness while planning your lines.

You do struggle with the back corner still which is fairly normal, you may find this example helpful. It shows how each line in a set relates to one another, the inner pair will always be nearly identical but the outer pair can have quite a bit of variety depending on how far the vanishing point is. A lot of people realize this intuitively through the challenge, but having it pointed out clearly can help solidify the understanding.

Overall I'm glad to see you develop a better understanding of 3D space as well as improve your line quality. I think you've shown more then enough growth and understanding to move you on to Lesson 2.

Great work and good luck!