Base file from https://3dwarehouse.sketchup.com/model/f818dd6e-9ff5-4f11-86c3-a55af05cf9fa/USS-Enterprise-NCC-1701-A but I felt it had some minor issues, the nacelles felt too narrow, ended with just a flat spot, and the bottom of the engineering/secondary hull seemed a little too truncated. I kept the same length of the nacelles but increased their diameter, put a cylinder relief in the back, extended the bottom of the hull back a little.