The hardest part about this project is making the leg and then multiplying that by 4, but if you can make one you can make all four. I won't be going over all the details to building the body of your robot, but I'll try to give you a general idea on how to do it.
As mentioned earlier the body is made out of balsa wood, which is a very nice material to work with, for all you need is a knife. Since I had a table saw available to use, I used that for some cutting rather than the knife to be able to get more consistent and parallel cuts. If you decide to use a table saw instead, please be careful and wear goggles.
I have add a drawing of one leg and several pictures so that you can use those to refer to when you are building the legs. One detail I will point out for the legs is the pivot point. You may see in my drawing there is a pin underneath the servo. This is to strengthen the leg, instead of having all the weight on the servo axle. This is where you will be needing the 1/8 drill bit and 1/8 dowel. As for the belly of the robot, its just a rectangle with notches on the corners to hold the servos.
I used wood glue to attached balsa pieces together, this creates a strong bond. You can also coat the balsa wood with wood glue to strengthen it. I used hot glue to attach the servos to the balsa wood, but I later found out that after a month or so, the hot glue begins to fail, so you may want to try somethings else if you want a more permanent bond.
If you have a better design, go for it. I choose this design because the robot has the capability of rotating its leg 180 degrees so that it can walk upside down.