I designed this unit to make a suction system for my lab and I've chosen a multi tube system. Picked up 40mm (ID) drainpipes (with integrated rubber gasket) and connected to chinese cyclone through this unit.

Use m3 screw secure the 4 fittings part and m5 for the 56 mm tube (ID) and use super glue or silicone to seal.

I still haven't finished my job, but I tested it and it works.