I went through and tweaked the onshape maslow design (cleaning up the CAD definitions)
I did a minimal modification to make a version that used a strong top beam instead of the angled arms.
This is a branch in the same onshape document, you can get to it directly at https://cad.onshape.com/documents/e635c24e358635f51da4b399/w/044390da4e634559b6692ad5/e/0886cbad72fe04c5caaee1dc
And finally I did a bit more tweaking and have what I think I will build. This is a folding frame that has wheels on it to make it easier to move in and out of my garage and use as little space as possible while stored. I’ll probably add a large whiteboard to the back legs. I will put rope or chains between the front and back legs to limit how far it opens (and thereby adjusting it’s angle)
This is the easiest to build as it has nothing other than 2x material cut to length (except the sled and brick holders) I ordered a LVL beam from my local lumber yard for $35, so the top beam will be nice and stiff.