UK down pipe reducer 68-25mm

My friend designed a fantastic solution for diverting rain water in tight spaces and this can also be converted to perforated tube section to make custom French Drain. Rainwater reducer descriptionI wanted to connect a standard OD ø68 mm rainwater downpipe into a standard ID ø25 mm flexible aquatic hose (/Corrugated Pond Pump Pipe). My application to route rainwater collected from the roof underground via the cheap/easily buried flexible hose. I call it micro-bore drainage 😂This printed reducer design relies on a flexible print material (e.g. TPU), to enable compression fits and intent is to use jubilee clips around each interface to secure the connections.Flow rate testing: tests proved that a 15 m run of the ø25 mm tube laid horizontally, could shift 25 litres per minute! This assumed that the attached vertical rainwater downpipe was able to accumulate ~2 meters height of w