be like painting the Forth Bridge

be like painting the Forth Bridge (British)

if repairing or improving something is like painting the Forth Bridge, it takes such a long time that by the time you have finished doing it, you have to start again. Home improvements are a bit like painting the Forth Bridge. By the time you've finished the kitchen, the bathroom needs decorating and so it goes on.

See also: bridge, forth, like, painting