The older I get, the further down I have to sit, it seems. Being on a disability pension, I was looking for a way to make my couch higher. I have seen blocks made to increase height, but they are very costly. Instead, I unscrewed a leg and took it with me to a hardware store. I purchased a piece of plumbing pipe (black) that just fitted over the wooden foot, increasing the height by 5 inches. For a couple of dollars, I purchased enough pipe (4 x 10 inches) and was able to alter my sofa, a change people notice but can't quite put their finger on. Simple, simple, simple.
The pipe length quoted was 10 inches (high/long) x 4 pieces (to go over the original legs.) This is plastic PVC or something similar. Hope the picture helps.
My couch had short square legs. Several years ago my husband was struggling to get off the couch so I bought a length of 4" sewer pipe at Home Depot and cut it into even sections and placed it over the legs that were there and it worked perfectly and looks like the legs came with the couch. I cut my pipe into 7" lengths and it was a perfect height.