This 3D Model can be used as a shisha diffuser. It is modelled with OpenScad and can be modified (e.g different pipe diameter).

Print Settings: I have printed the shown diffuser without support material. I also used the pipe hole as a stand and a skirt of 0 with 6 rounds and a layer height of 2 for stabilisation, which I cut off after the print (Infill is set to 20% but I think it doesn't matter)