I wrote this for !zerowaste but it kind of feels like a better fit for diy.
https://i.imgur.com/oBgXyBW.jpg
I don’t have any in-progress pictures of this one, but it’s such a simple design I doubt you'll need them. I responded to a post on the local Everything is Free page where a guy was cleaning out all the lumber left under his porch. At the end of the week he had a dumpster coming and anything that hadn’t been taken he would throw away.
I loaded up my car with what I could fit, but there was this big roughcut 2x12 plank that looked like it had been used as scaffolding (paint marks and boot prints). It was too long to fit in my car but he was renting a chopsaw with the dumpster, so he offered to cut the board to length when they showed up and set it aside for me. So I was able to go back for it (ever since, I’ve brought saws, a tape measure, a square, and a marker with me whenever I pick up lumber). I asked him to cut it to a six foot length, and he even saved the extra for me, which worked out well because I made the rest of the bench out of it.
After having spent some time restoring fancy furniture, I wanted to try something more rustic. I cut the leftover material into three pieces, two legs/sides, and one square piece to cut in half diagonally for support. On the two uprights, I cut a decorative notch in the base, and tapered the sides. I had to use a hand saw for most of this as the skillsaw didn't like the thick plank.
https://i.imgur.com/akUnIBT.png
I nailed down through the top into the legs, then flipped it, put the 45s in place and drove screws through the angled surface into the legs and the underside of the bench. Then I drove screws in from the outside of the legs, and nails through the benchtop.
I gave the benchtop and sides a very casual sanding, just to knock away any splinters and rough spots, and urethaned it so it would last longer.
It's not as pretty as some of the things I've made, but it's strong, and simple, and was made out of wood I got for free and screws/nails/urethane I already had.