I have constructed the center hoops, lots of clamping and drilling.
The width measurements are pretty close, but the height measurement is out by about 4/32, I can't image that this will cause a problem, guess I'll find out when I start to fit it to the fuselage.
The 4 hoops drilled to teh center joiner strips
Fairly symetrical
Center joint plate back drilled to front and rear hoops