US Pipe Fittings Creator

I took Paul_Tibble's SCAD file where each connector type is a separate file and made the following changes:

1. Made one file that allows you to generate all 6 connector locations (top, bottom, front, back, left, right)
2. Each connector location was made with its own inner diameter to allow for reducers and connecting different-size pipes together.
3. Allowed each connector location to display or not display
4. Added Standard US OD pipe sizes from https://www.pvcfittingsonline.com/resource-center/pvc-pipe-od-size-chart/ up to 6 inches.