This diffuser prints upside-down and does not require supports due to the 45 degree slope and angled diffusion holes. Plenty of perforations on all sides to let the water out quickly while not disturbing the bottom of the aquarium. Feet keep the diffuser level and create a space for additional water to flow out towards the aquarium wall. 
 

Six versions are available: 

• For up to a 20mm aquarium rim:
  • Nano - 60mm x 50mm x 105mm
  • Small - 80mm x 70mm x 125mm
  • Medium - 100mm x 100mm x 150mm
  • Large - 130mm x 110mm x 160mm
• For up to a 30mm aquarium rim: 
  • Medium - 100mm x 100mm x 150mm
  • Large - 130mm x 110mm x 160mm

Prints well in PLA with .24mm layer thickness, 4 walls and 15% infill.