One of the fabrication challenges would be that every one of the slats is a different size.
Maybe you could do the profile on the ends, and then just lengthen and thicken the middle of each slat appropriately?
Nowadays with a water jet, or a laser cutter, if you could build one out of cardboard you would have a good template.
Once you know the basic sizes, cutting the slats, profiling the ends and designing the stringers might not be as big of a project.
With a CAD Program, you could copy the profile and cut/paste it onto each one of the individual slats. The two stringers would be identical.
Leave a tab at the bottom of each of the stringers that you could bend over and install a grommet so you don’t tear up your paint on the back deck lid.
You could use quick release pins through the bottom of the grommets into the deck lid to retain it (assuming a hinged design).
You could probably use black powder coated stainless steel hinges to attach the stringers to the slats. Removing the hinge pins, and use some sort of thin, removable sliding pin would facilitate assembly/disassembly.
I do agree a design hinged at the top would be a lot easier to keep clean.
I think Wade (Mk4-4280) had built some as one of his businesses (LoFlyte) back in the day, but I never saw one in the flesh.
Let us know if you get all motivated and do such a project.
Or as Doug suggests, let us know if you found a brand new uninstalled Mind-Train version that somebody has had in their grandfathers garage for 35 years… it has happened!
Rocky
OBTW: There’s a lot of great design information in that Mind-Train catalog if you’re gonna consider this project. No sense in reinventing the wheel.
I doubt if it’s patented or copyrighted, and if it’s published (like in the catalog) they can no longer claim it’s a “trade secret”!