Summertime also means bees, flies and beetles. And no one wants to have them in his bottle.(Tested with EU bottles)

3d printing to the rescue.

Print instructions

Category: Household Print Settings

Printer Brand: Prusa

Printer: i3 MK3

Rafts: No

Supports: No

Resolution: 0.2mm

Infill: 0%

Filament: Das Filament TPU (90 - 94A) Schwarz / Black
Notes:

I used TPU only once before, so I'll played it save. No retraction, no Infill (not needed) and I went slow... 20mm/s. Jip - that slow. But it worked out fine. Almost no stringing, perimeters are fine. and print time is okay.