Print it in the orientation in which it is generated (upside down). Strength-wise this is not a very demanding object (1 shell is ok, 2 if in doubt). Nozzle size or layer height don't matter much. 5 or 10% infill is ok.

Mix to attract and drown fruit flies:

• 2 tbsp molassis;
• 2 tbsp apple cider vinegar;
• 3-4 tbsp juice concentrate (orange or apple will do fine or other sweet juice concentrate);
• 1/4 cup water;
• 2-3 drops washing-up liquid.

Stir gently so it doesn't foam and pour the mix into the bottle.
Place the bottle where there are a lot of flies and watch them drown in the mix. ;)