This is exteder for pulsio AIR, I have printed it in PETG, all walls. 

Since every filament has shrink factor, first print only top part until you find proper size, mine was 99.8%, Also I made sure seam is minimal. Do not put it too tight, as it will be very hard to remove, and do not put it too loose as your Pulsio will fall out. 

Extender length is 17cm

Nozzle 0.6, 0.3layer height 

Temp 250

10walls

PETG