Hi, ItsMartin. Just took a look at your exercises and, while they're overall good, there's a few aspects you should pay more attention in order to improve.

Your lines are noticeably arching. This can happen when you're not using the motion of the shoulder to draw. If you mix some elbow motion, the lines tend to arch.

On your ghosted planes you didn't plot the inner lines. Always place dots before drawing each line, as this will work as a goal to draw your line to. Having goals ike this can make you notice your mistakes better and help you improve.

One thing I noticed on your ellipses is that you're not drawing through them. Always go another time over each ellipse. On your funnels exercise, some of your ellipses are not well aligned to the minor axis (central line).

While your rotated boxes are overall good, you could have shaded the sides better. Hatching should be done consciously. Each line you draw during hatching is a line your practice. In this exercise I also noticed that in some occasions you wen over the same lines more than once. Plot your lines with dots, ghost them well and draw each one only once.

Your last exercise is also good. It has a nice composition and you took the risk in overlapping some of the boxes. One think you could have done was slightly increase the line weight of the overlapping lines in order to highlight that they are in front.

Good job in this lesson and good luck on the next ones.