So from what I understand you find lesson 7 difficult due to the lack of reference angles available for the vehicles / available tutorials. Before I answer your concerns I would recommend to skip drawing the demo's as they involve outdated approaches which uncomfortable will probably update in the future. I would still recommend you watch them to learn how to utilize the techniques introduced into the lesson (like repeating measurements and drawing a circle in perspective). Reading the text and the lesson 6 demo on orthographics will help you more.

The critical aspect about lesson 7 is orthographic studies of the vehicle, both front and side views are pretty much essential if you want to construct the vehicles precisely. Usually with lesson 7 this involves a bit more guesswork when making the orthographic plans (due to the limited amount of references) but that is completely fine for 2 reasons. The first reason being that the orthographic plans are merely to set our intentions of what we're going to draw and where we will draw it so that when we are constructing the vehicle we don't get distracted and can focus on the hard part of the exercise which is thinking in 3d space. This means that it doesn't really matter if the wheel of a car is either 21/50ths or 23/50ths because as long as it looks like a car and the proportions are roughly correct then the measurements don't really matter, its all about setting the intention of where you will draw something and sticking to it. This also ties into the second reason being that it's okay if the vehicles don't look like the reference or they look out of proportion because at the end of the day these drawings are just exercises to get us thinking in 3d space so it doesn't really matter if they look bad.

With that being said the lesson does get easier if you get more/better references but it is entirely possible to do a construction with just one photo (I did it here) which just goes to show that the orthographic views are what is most important.

It also seems like you want a step by step approach to the lesson, so here's what I think the general procedure for each vehicle should look like.

1. Gather references of the vehicle so that you can at least see the front and side of it.

2. Draw orthographic views either starting with the side or the front and make sure the details line up on both and making sure you measure the car in wheels as that is the only accurate/precise measurement you can do (usually this means getting a circle template and using a circle as "1" wheel. An example of this is on the double decker bus I posted earlier where you can see that I measure it as 4 wheels wide and 4 wheels tall using circles, from observation.). An important note about drawing the front view is that you want to account for distortion as it can seem like the car gets wider the further back it goes which isn't the case. The views can be done digitally if you find that it's easier although I recommend doing it on paper as it can train your observational skills.

3. After you've drawn your front and side views you should draw a horizon line on a new piece of paper first and then either draw a bounding box for which the vehicle will be drawn in or draw a box for the front and then draw a box for each separate piece of the vehicle like uncomfortable did in the cab over truck demo I personally only ever did a bounding box for the whole vehicle so I'm not sure how the other method would work. For the bounding box to be accurately measured to your vehicle you need to use an ellipse template to replicate how many wheels wide / long / high you drew it on in your orthographic plans and instead of circles they are now ellipses as we are drawing in perspective.

4. After you've drawn the bounding box specific to your vehicle you can now replicate your orthographic side and front views and if you've lined up the details on both views it should look like half a vehicle. After this point you have to extend the lines in 3d space and figure out how it would look like which is the hardest part of the exercise.

• Important notes

• This "step-by-step" assumes you are going to use a bounding box to fit the vehicle inside

• This method is extremely time consuming (constructions can take up to 20+ hours depending on how far you take it) so make sure you take it at your own pace and not rush them.

• look at other lesson 7 submissions who construct accurately (here are some including mine | https://imgur.com/a/8Fxz7Y2 | https://imgur.com/a/HbYG4k4 | https://imgur.com/a/oO6707p ) and try to figure out how they constructed the plans and vehicles with subdivisions and try to reconstruct it in your head. These submissions go through pretty much the method that I described above (as far as I can tell). If you are really stuck you can try use one of their plans and try to construct the vehicle yourself from it as practice for drawing the construction.

• always use subdivisions and make sure you can replicate every line you make, if you want some tips on subdivision I made a reply to another question which gives tips on how to subdivide effectively here

• even if you follow the step-by-step method and look and understand other constructions you might be confused which is perfectly fine, this lesson is the hardest and might take a while for you to fully understand how to do it. I only understood how to do it well after my 5/6th vehicle so as long as you keep at it you will understand eventually.

• always break down curves into a chain of straight lines, most students forget / miss this instruction so it's worth repeating especially for lesson 7. The reasoning for this can be found here

• I probably missed something given I've wrote it all from my memory of doing lesson 7 so if anything is confusing or you have any questions don't hesitate to ask