Wicked stuff here! Really dig the fact that you're practicing your ID drawings the traditional. Something I should do more often.
A few crits would be: sometimes your design have a slight wonkiness to them, which I think give them character but takes away from them feeling stable. Watch the outlines, they can be a bit thick sometimes. However, taken as a whole drawing, it reads like it should but I think scaling down your lines overall would help the drawings look more pro.
Overall, nice work and cool designs!