More (semi) Scrap Wood Carpentry

I returned to my scrap wood carpentry hobby the last few weeks. I have looked online at various web sites about carpentry, trying to actually learn something. As I expected, it starts to get pretty complicated as soon as you get past the idea of screwing two boards together. Beyond the construction and finishing techniques, you have to take into account the properties of solid wood, which will expand and contract significantly with temperature and humidity. There seem to be limitless (expensive) tools you need to do any serious carpentry. I am going to try and make do with my circular saw, router, drill and sander (nice ones that my father got me over the years), and the odd hand tool I have already. Somewhere in the back of my mind I had hoped to build up enough skill playing around with scrap wood to be able to do some kitchen renovations we have in mind on my own. I just don't think that will happen now, we'll have to get a professional in. I do have a few things I'd like to make on my own still, for fun - and the higher content of scrap wood the better (you'll see below that I have had to actually buy some wood for my latest projects). I want to at least get to the minimal stage where I can build a few custom things to fit specific spots in our house that don't have nails, screws, or gaps between the boards showing. This seems to be one of the minimal goals of furniture making. I haven't been following plans, a lot of the fun is coming up with the design. 

The two things I made recently are a computer desk that fits in a particular, narrow gap, shown on the left below. On the right is a workbench. I made it with the gap in the middle for long rip cuts and the same height as a commercial bench my parents in law gave me a few years ago, so I can use both for bigger pieces. I may have to tinker with the arrangement of the top boards to allow room for clamps as I start to use it, I just don't have enough experience yet to know where they will be needed while arranging pieces for cutting, routing and assembly. Notice the off centre middle support on the bench. I used ideas from advanced geometry to determine the most aesthetically pleasing location. The tops of both pieces were made of new boards I had to buy for about $30.