Its the same size as a happs trackball plate.
As for the approach, there is a reason that its done that way. Its the smae design type as the original - which uses an x shaped rubber centering device.
I tried using a realy heavy spring, and it wasnt the same. You see, the force is pivotal and stays in the very center. Once you get the thing in motion (out of the center) the force is the same everywhere. This means, its too easy to move to the outer edge.
The best way to describe this... Think of a brake -vs- a gas peddle. The gas pedal has a spring... but even if it was heavy, its still pivotal. Once you get it past the main pivot, its easy to press the pedal down with the same amount of force.
A brake however, uses a compression method. It gets harder to push the pedal down, the further you push it. It may take 5 lbs to push the peddal a cm, but 30lbs to push it in at 4 inches.
The way the spider works is that if you go left... you are fighting 4 bands.... though, the closer bands will be easier as they arent streched as far as the further bands - making it harder to push the further you go.
This is a HUGE factor in how the game operates... and nothing else will work effectively. Trust me, I tried
A smaller, more efffective x shape, would reduce the size... although, its not easy to come by such material. The guy who makes a replacement for the real machines, wouldnt make one the would fit the shaft I was using... because it wasnt cost effective.