For the first 50, your lines are smooth overall, though I see instances of arcing here and there, like box 9, box 30, and box 46. Your convergences also show good accuracy, though I noticed some lines pair off and converge towards two vanishing points, like box 4's red lines, box 24's orange lines, and box 43's green lines.

For the next 50, your lines show improvement, with fewer instances of arcing. However, some are still present, like box 52, box 76, and box 91. Your convergences also show improvement, though I see more instances of lines pairing off, like box 58's green lines, box 82's blue lines, and box 98's orange lines.

For the last 150, your lines continue to improve. There are fewer instances of arcing, and most are less dramatic outside of instances like box 109, box 165, and box 208. Since arcing is present throughout the challenge, I do recommend double-checking your technique. However, the improvement tells me you're on the right track.

Your convergences also show continued improvement, though there are still instances of lines pairing off, like box 119's orange lines, box 175's blue lines, and box 232's green lines. In these boxes, the inner lines (green and orange in this diagram) diverge instead of converging at the vanishing point. Keeping in mind the angles of neighboring lines can help when planning the box's construction.

As an aside, box 6, box 75, box 99, box 120, and box 185 appear to be missing some line extensions. Box 129 also has some lines extended in the wrong direction. It's not a major issue since it didn't happen often, but I want to point it out for future reference.

Also, some of the pink and yellow lines did not scan very well; they seemed to disappear in places. If you have darker shades available, I recommend using them in the future.

All said, I'm going to mark this challenge as complete.