if you must fabricate. you may consider existing abs or pvc plumbing t's or y's of a similar diameter for a jumping off point to connect to flex tubes. easy to cut and glue and drill for a diverter. Necessity is the mother of invention.

Larry
Old man᠁Old truck᠁neither one goes very fast. All you need in life is TIME, PATIENCE and MONEY.
If you are missing one component, you'll need an abundance of the others two.