Farmers have been doing these things for years out of necessity. Just happens to also be good for the environment.
Here are some examples from my place.
Milk jug cold frame. Made on top of one of my little 4' X 4' raised bed gardens. Fill milk jugs or other containers with water. Either put black food coloring in the water or paint a dark color. Place the jugs as desired in the greenhouse. I place a stick through the handles of mine to form a sort of ridge. Find a conveniently sized piece of sheet plastic and drape over the jugs and garden area.
The jugs elevate the plastic to allow for plant growth and the water in the jugs stores heat and helps keep the bed above freezing at night.
Here is an old rubbish bin which has been converted into a compost bin. Nothing extrodinary here. Again just using what I have versus going to the store to buy. Drill lots of large holes in the bin to allow for air circulation and to minimize anerobic versus aerobic decomposition. This compost bin is nice since it is on wheels and can be moved easily as needed.
We didn't all move to the country just for work. We enjoy recreating too. Here is an improvised bicycle kayak/canoe trailer. Very good way to use bits of this and that. You'll need a couple of wheels, some lumber, some scrap aliminum, a piece of sheet metal or fiberglass for gussets, some u bolts and some nuts and bolts.
two main components. T-shaped tongue and wheeled platform. I use small ratcheting straps for the connection. The hitch is simple a V cut in the end of the wooden tongue. A hole is drilled across the end of the tongue and a bolt is insterted to attach the trailer to the bicycle seat post.