Was able to spend about an hour in the garage tonight after the family Easter Celebrations. First thing I did was cut out a square around the drawn disc I created yesterday. I then nailed the square down via its center point. This allowed me to spin the square. Using my hand jigsaw, I was able to cut into the square, hold the saw firm and spin the square around it's center point, following the drawn 18" circle. The cut was pretty darn good for being done by hand. After I finished, I sanded all the edges. I didn't take a picture of the square cut out, but you can see the remainder of the plywood under the disc in this photo. You can also see the disc is still nailed down by it's center point. This was right after I finished cutting the disc.
Also, in the above photo, you can see I had drilled a hole on the inside of the disc so I can insert my jigsaw to cut out the center portion of the disc. Here's a cleaner shot of the hole with all the sawdust blown away.
Here's the remnant square after being lifted from the disc.
And lastly, a shot of the top ring itself at an almost perfect 18".
After all of this, I began laying out the design for the bottom disc. I think I have most of the angles drawn in, the center foot square dimensions and the flat spots on the sides of the ring. Pictures to follow when I get back to it.
Ya know, I forgot how theraputic working with wood can be! And...R2 is getting his skeleton!