Depending on our skill and desire many complex special tools can be made. It may be as simple as heating up a combination wrench with a propane torch and bending it into a special shape to cutting and welding steel into a complex special tool.
When hunger forced me into working on three and four wheel ATCs I found a lot of them had huge nuts on their rear ends. I found I could hacksaw one side of a thick open-end wrench off, weld a piece of metal in and whala! A Special tool.
You can take wrenches, cut the end off and weld that end to a socket and bang, another special tool.
To make big sockets measure the side of the nut and cut six pieces of one inch wide, quarter inch thick, steel strap. place the pieces of steel around the nut and wrap it with some wire. Then weld. You can make all kinds of big sockets this way. Weld an old half inch drive socket on it and you have a big special socket. Need it to be real deep? Weld a length of steel pipe on it and then weld the socket on the other end.
You can make quite a complicated special tool. I had a wheel come in last year for a new set of bearings. Easy job right? Not! It had a special aluminum nut with six slots on it. Why they couldn't have used a nice, easy to remove circlip I don't know. So I cut up some steel strap and welded the pieces together. Then I welded an old nut onto it and boom. A dandy special tool that worked great. Same tool from the manufacturer, $60-80. After market, $20-25. Cost to make? Basically nothing but I did have to clean some rust off the strap steel I used!
So with a bit of welding, you can make a lot of special tools and save a lot of money. If you don't have a welder you can still make a number of special tools just by heating a wrench with a propane torch and bending it. If you have a lath, wow, the skies the limit.