How long is a piece of string?! The truth is, it could be any length but if we break down the different processes and put a time on them we can come to some reasonable answer to that question.
The cureing of the goatskin; It takes 6 to 7 days to lime the skin in a bucket and then it will need to be pickeled in brine for two days. So lets say that the skin is cured in 9 days on the outside.
Within that time one should be able to manufacture a frame, even a tuneable frame varnished and finished with adjusters ready to receive a goatskin.
It will only take an hour to glue or staple the skin onto the frame. Then we must allow the skin to dry. This could thake 4 to 8 hours depending on humidity and it is very important that the skin drys naturally, so lets go with the outside time of 8 hours.
Now add it all up, 9 days to cure, one hour to skin and 8 hours to dry.
The answer then, is somewhere around 9 days and 9 hours to make a really great Bodhrán drum.