You can download the SketchUp (version 2017) model I made here
Feel free to copy and/or modify it, and if you actually build them please let me know how it went. Send pictures! And of course any suggestions for improvements are welcome - especially if you happen to have a solution for my "height adjustable" puzzle :-)
I didn't add any dimensions to the SketchUp model, but you can easily get those yourself of course. And depending on the materials you use, you may want to change those anyway. I used an 18 degree angle for the legs, and the sawhorse is about 80.6 cm high when unfolded, and 93.6 cm wide, but of course you can play around with that too to suit your needs.
I made the design for 18mm thick material, but that can also be changed relatively easily if needed. I used some leftover 18mm and 15mm plywood, and 20mm wooden shelves, for my build because that's what I had lying around. If you happen to have some 9mm (or thereabouts) material, then you might consider sandwiching that to create half-lap joints for the legs, to join the horizontal and vertical parts of the legs. That would make the legs even stronger (and easier to build) than using dowels for example, which I did.
Also you may want to adjust some things for the hinges you use. I used quite small (and cheap) ones from Amazon, that's why there are 10 hinges per sawhorse. If you have some sturdier ones you can probably use less of them. Just make sure you account for any extra thickness of the hinges, so the sawhorse still folds flat.
If you look closely you will notice the SketchUp model is a bit different from the actual sawhorses I built. Along the way I improved some parts of the design as I built it, so the model is a slightly better version than the actual build.