Now we are ready for final assembly. Begin the assembly by placing an O-rings around each wheel and confirm that they are properly seated in the grooves. Next, cut the dowel to the appropriate lengths - this will vary dependent on the thickness of your washers, and the depth of the axle caps. Getting the proper length of dowel may take some trial and error. Note that each joint adds some friction to the system and the sum of all of that friction combats the proper functioning of the toy. The goal, then is to minimize this friction and the easiest way to do this is to ensure that the dowels freely spin in the places that they should. If you need to decrease the diameter of a dowel, you can pinch a short lengths between your fingers (one end of the dowel on your thumb and the other on your forefinger) and sand the dowel until you have achieved the desired diameter. The wheels should be assembled out of phase: so if the left front wheel connection point is at the 3 o'clock position the right front wheel connection point should be at the 9 o'clock position. Wherever the dowel is to be fixed, place a small drop of glue into the press-fit holes shown in the pattern (in the body, in the wheels, in the tops of the thighs, and in each axle cap). Use a washer at each and every joint to space the pieces apart and to minimize friction. Note that washers are not required between the wood and the axle caps.