Yes, a booklet about designing type, the entire text of which was completely handwritten. Quite a sense of humor, that Dwiggins. ;-)

Digitized and available for viewing: http://archive.org/details/WADtoRR1940

a booklet about designing type, the entire text of which was completely handwritten

One of a select genre, along with Jan van Krimpen's letter to Philip Hofer. Any others?

{Sorry - honest mistake.}

But Catich, I believe, wasn't writing about type design. There are quite a lot of books on calligraphy and other kinds of lettering that are reproduced from manuscript. But surely few on the subject of type, and those, if the two so far listed are typical, epistolary.

{Sorry - honest mistake.}

John — Was the Van Krimpen–Hofer letter reproduced from the original? or re-composed, as was the WAD–RR book?

It's a facsimile of the original letter, along with a redundant typeset transcript, but the letter is really a formal manuscript, not a typical epistle.

John, this isn’t “a booklet about designing type, the entire text of which was completely handwritten,” but it is still in the same universe, I think:

Edward Johnston, Mark Argetsinger, David Pankow: Thinking in script http://carypress.rit.edu/publications/books/thinking-script.html

This is a letter from Edward Johnston to Paul Standard, reproduced by the RIT Cary Arts Press in facsimile—in book form, instead of letter sheets. It is a quite nice little thing.