Converter for Japanese Water Fountain tube

After printing the awesome Japanese Water Fountain / Deer scarer at https://www.thingiverse.com/thing:2875176 and getting some parts I found out that the tube I got was fine for the pump I attached it to, and the pump connected just find to the fountain base, but the other side of the tube needed to be way thicker.
The outer diameter of my tube was a measly 6mm where it should have been 11-ish for a proper seal. I didn't feel like glue/silicon sealant was going to fly here, so I designed this c