Beer bottle cover for brewers

See notes below*
With thanks for the idea from Stuart Davison on the Pinter Facebook page.
This small cap is intended to be placed over crown cap beer bottles, after the beer has been drunk, to keep the dust and nasties out until needed again next time.
Best to wash the bottles out first, and then use the cap.
Each cap takes 9 mins to print.
This cap is not a replacement for Metal crown caps. You cannot use this cap as a substitute for the metal crown caps for the storage of beer in the bottle.

*THIS IS NOW THE MARK TWO VERSION
When using the Mk.1. caps I realised that the bottles I was using had neck width differences of up to 1mm. The revised design copes with this problem.