The nice thing about cutting your own ribs is i you screw 10 up, you can easily cut 10 more, unlike laser or CNC where you don't have the template to cut yourself a new one.

What I do is if the ribs are all the same, I make a template out of 1/8" aluminum sheet so it will never get damaged, and I can run the exacto blade or pen around the rib without putting a big dent in the template. I then simply use the band saw and sander to cut the rib out.

Takes longer, but when that airplane takes off, its a little more rewarding.

Jason