At one time I tried to make a list of all the different kinds of processes involved in making crafts. It was quite long. Today's process in building the armchair is what I call an additive process. I am making the posts which will be the legs and corners of the chair.
What I am aiming for is a 4x4 post (actually 3.5 inches by 3.5 inches), with notches. I could take a 4x4, and saw and chisel out the notches. That would be a subtractive process, and would involve spending money on 4x4s and doing some careful cutting work. Or I could take the 2x4s that we already have, do a few simple cuts, and assemble them into an equivalent form:
The result is 3.5 inches by 3 inches, because a 2x4 is really 1.5 inches by 3.5 inches, but I have accounted for that in my design. I used both nails and carpenter's glue for assembly, and even drilled pilot holes for the nails, to avoid any chance of the nails splitting the wood. (For the couch, I used screws instead of nails, but we are running low on long screws at the moment.) The nail heads are barely visible in the photo. For the pilot holes, I drilled through the top piece first, pounded the nail through until it stuck out slightly, and used the point to mark where the rest of the pilot hole should be drilled. After drilling all the holes, I put the glue on, replaced the pieces, and drove the nails home. The nails aren't really necessary; the average carpenter's glue, when dry, is much stronger than the average cheap wood.