In September 2020 I needed some sturdy sawhorses, so I started to look around for suitable designs. I found quite a few nice ones, but none of them were exactly what I wanted. And since I also wanted to work on my SketchUp skills, I decided to design my own sawhorses, combining some of the designs I found with my own ideas.

My list of requirements:

• Foldable, since I don't have a lot of room to store them. I made them from (mostly) 18mm plywood I had lying around, so the thickness of the entire sawhorse is 36mm when folded.
• Sturdy enough to support a granite kitchen table top (you guessed it, that's why I needed the sawhorses in the first place) - I can lift the table top on one side with some effort, so I'm guestimating it to weigh a bit over 100 kg. I tested each sawhorse by standing on top of it, and they didn't budge at all - so no worries there.
• Must have no tendency whatsoever to collapse, even if you happen to kick one of the legs. The platform hooks over the bottom rail, so it is kick-resistant in all direction (except up of course, so try to avoid that...).
• The platform should also be usable as a step stool and as a place to put tools and other stuff. Also tested that one - no problem, even jumping up and down on it was fine.

I also looked into making it height adjustable, but doing that - while still keeping it foldable and sturdy - turned out to be quite a challenge. In other words, I haven't figured out how to do it yet :-)
So I saved that one for later - if I ever really need it, which I don't know yet. The top bar of the sawhorse can be replaced easily, so modifications should be relatively easy.

My Google research provided some nice designs and ideas:

• "How to make Foldable Sawhorses - Strong and Super Compact!" by Alexandre Chappel
• "How To Make THE BEST Folding Saw Horses" by John Heisz (I Build It)
• "Folding Sawhorses | STEP BY STEP with limited tools" by Steve Ramsey (Woodworking for Mere Mortals)
• "Adjustable-height folding saw horses" by Christopher Merrill
• "Folding Sawhorses" by Lumberjocks
• "How To Build An Adjustable Sawhorse" by Family Handyman

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.

Click on the images to enlarge.

Folded and unfolded.

When folded, the platform is hinged upwards, and held in place between the piece of plywood on the inside of the front leg and the small stop block on the inside of the back leg.

The top bar is attached to one leg, and is supported on a notch in the other leg when unfolded. So the bulk of the weight is carried directly by the legs themselves, not by the hinges.

The platform is supported between the hinges by some extra blocks of plywood, so the hinges don't have to do all the hard work.

Note: After storing them for a few weeks, I had to do quite some sanding to get them to operate smoothly again. So don't try to be too precise during the build - leave a small (2mm or so) gap between the legs and the platform, to allow the (ply)wood to contract or expand over time (caused by humity changes and/or temperature).