I manage multiple Twitter accounts. At some point, I will need to retire one; let’s call that Account A.

Is there a tool which will allow me, with ease, to make my Account B follow all the people currently followed by Account A?

Some people may find it useful, too, to be able to create a new account and have it follow all the people followed by an existing account which they or a third party own.

If there isn’t such a tool, would somebody care to make one?

Any such tool would need to deal with any duplicates (i.e. people already followed by Account B); and perhaps any limits set by Twitter on the number of follows made in a short period.