He hasn't teach us (yet) the tricks to figure out the vanishing lines. We are just experimenting and getting loose, comfortable. At this stage we are allowed to make those mistakes, get frustrated, and create 'core memories'...lol. When we fail we appreciate the solution more, so it will stick in our brains. No pain, no gain. On the other hand these arrows look fantastic, and they are free hand! Give yourself some credit. You are doing exactly what we should be doing at this stage.

For the hexagon, I kinda deconstructed what Marshall did and drew a box around the form using the edges of the hexagon to discover the 3 axes which give you the box. Then I divided the planes of the box with diagonals to find the halfway point for the hexagon, and finally just connected them. I found the other side by using the parallel axis lines along a particular axis. I hope this makes some sense, I tried but it’s a lot of lines so I apologize if it’s confusing. It’s simpler than it looks to try, much harder to get perfect (intuiting the VPs), but not a hard system in itself, just lots of lines. Basically sussing out the 3 axes and diagonals then a lot of connect the dots. So you were right to look for VPs, we just don’t need to find them for the slanted xz lines because discovering the centre point with the diagonals method give us the result quicker. The diagonal method is a reliable way to get halves or thirds or more in perspective where halves for example get smaller further back and don’t look like exact halves. I use the same methods for the shape that shall not be named, I try to find the axes in common with a box, and start there. For the second image in your post, that will come up when we begin to do accurate proportions I think so I wouldn’t worry about that yet. Rn I’m just estimating some parts from the diagonals and axes method above.

Great suggestion with the transparent forms and great assignments 👏