1. Table Saw - Set the table saw blade at 5 degrees to cut the sides of your block. I also use the table saw for cutting my scraps into inlay material.
2. Drill press with forstner bits. Set the drill press to the slowest possible speed and use forstner bits to remove the majority of the material that creates the channel inside the call.
3. Dremel tool with 1/2 sanding drums at 60 grit - After I drill out most of the material I use the dremel on a relatively slow speed to clean up the inside of the call.
4. Belt sander or equivelant - i use three different sanding belts, 50, 80 and 120. All depends on what wood species I am using.
5. Chisels - Some prefer to use very sharp wood chisels to hewn out the inside of the box. I personally do not prefer this method.
A band saw is nice to have, if you have one you will know why. I also use my huge and mighty powerful 12" miter saw for squaring up the ends of my 2x2" stock prior to cutting the 5 degrees on the sides.
For dimensions and measurements, copy your favorite box call. Measure it and do your best to copy it. A lot of call makers get all outraged when they hear the word, "copy". They seem to have forgotten how they first got started. Not too mention most of them copy the Neil Cost box down to the checkering. Copy your favorite call until you have the fundamentals down.
The fundamentals being the shape. Tuning the call is a whole new process. The curve of the sides, the thickness and curve of the paddle and thickness of the sides are all things that you will mess with when you tune the call.
Once you make a dozen calls you will be comfortable with the fundamentals and will then begin working on your tone and the tuning process. You will probably end up making another couple dozen calls before you realistically start to find your own design.
Use black walnut for both the paddle and the lid for your first dozen calls. Unless of course you have other wood that is cheaper. Black walnut is garbage wood in my shop, so i use black walnut to practice ideas on.
"Instruments of Mass Destruction"