Ones that fold into benches would be really handy for workshops.
We had a couple different one over the years, a couple key points:
The slope of the back and seat have to be just right to be comfortable. The seat shouldn't be level when in bench mode, very few adjust the seat angle.
The top has to be TIGHT when in table mode. Most use a peg in a hole that gets sloppy over time.
Getting the balance between strong enough to feel solid and not too heavy to move without a forklift is also tough.
"You must be the change you want to see in the world." "First they ignore you, then they laugh at you, then they fight you, then you win." --Mahatma Gandhi
"Preach the Gospel always, and if necessary, use words." --Francis of Assisi.
"Family farms work when the whole family works the farm." -- Adam Klaus
All of these designs require reasonably flat ground. Most of mine is not flat. As I read through this thread, I realized that I need a one man chair that can be carted around in one hand. It needs to be a tripod. The place is covered in trees. My chair needs only two legs. The third and the one that gives the whole thing stability is a tree. It's all based on a small log that forks into two branches. The fork becomes two legs. A live edge slab is the seat. Lean it against any solid spot where the top can't readily slide and it's a very stable lounge chair.
My beautiful drawing --- The seat should probably be mounted lower, so that the rear has two attachment points, just below the crotch. The two thinner sticks can be either branches that grew there or limbs from another tree that are attached. They will be in tension, so only need to be thick enough to be attached firmly. I hope I can find a specimen with all of the right pieces naturally occurring. This would make a chair with only 2 pieces of wood. A flat backrest could be added.
I'm in the city for a while, but this will be my first green wood working project. I'll pack it around when I'm clearing trails.
If this thing had a head, it would look like a waiter carrying a tray.
This is a picnic table I built for base camp. Not foldable but it does come with benches! As opposed to a standard picnic table design, the seats are unattached. They can be pulled off and used elsewhere if needed. A key element in the design is that you don't have to climb over the seat; thus allowing for a backrest. The table accomodates 2-3 people on each side which is more conducive to group conversation than a long rectangular table. It is still a bit wobbly though, I am trying to figure out how to brace the legs without cutting in on (human) leg room. The surface is unstained and unfinished, which means it's dirty from contact with food etc. A non-toxic staining method (i.e. coffee) could be pursued...
Every day, every season there is change, something new to observe, and constant learning. Permaculture has the dimensions of a life-oriented chess game, involving the elements, energy, and the dimensions of both life-forms and building structures (also with political, social, financial, and global implications).