Water bottle rocket launch latch

This is a release latch for 2 litre water rocket bottles. The latch is designed to slide over a standard 21mm (21.3mm/21.5mm/ 27/32") external diameter waste pipe used as a combined fill rod/launch rod and slides comfortably inside the neck of the water bottles. No seal is required for most 2L bottles but it's useful to have a seal to make launching easier.

The hinged parts are attached to the hinge plate with M2 x 12mm screws and you should slide a 21mm x 1mm O-Ring over the pipe and sit i