BH Gas Cap remover/ Gas Cap

thingiverse

When printing, just print at 50% infill or so with three shells, and you'll get plenty of toughness. If you want to cap it off permanently, I suggest scaling down to about 98% and adding some glue. It will be challenging to press on, but it's better than having it come loose during flight. The smaller models have holes in them for ventilation; unfortunately, the picture doesn't show this feature, but rest assured that it is there.