Similar to self-publishing here also the author is the publisher of his or her works, i.e. he or she takes full responsibility for the publishing of his or her book, and bears the legal and financial risks associated with that.
Another case of self-publishing
In contrast with self-publishing, however, where the author may employ professional services for one, a few, and even all stages of the publishing process, with do-it-yourself publishing, the author is are capable of producing the final product all (or almost all) by himself. E.g., he/she can layout his/her text and illustrations in MS Word or a similar popular software product, print it on his/her home printer, and bind it himself/herself or at the nearby print-shop or copy centre. The connotation in this case is rather a non-professional product.
In contrast self-publishing as used here implies a professional product, often indistinguishable from the ones produced in a commercial print house. Therefore it depends on a number of professional services and/or service providers (to complement one's individual publishing-related abilities, if any).
Why "do it yourself"?
There are numerous reasons why you revert to self-publishing. All of these apply to do-it-yourself publishing as well. They are: the limited sale potential of the product, the case of a niche publication, the ability to retain complete Control over the publishing process and the possession of the copyright.
The basic reason, which may lead an author to "do-it-yourself" publishing is purely financial. Unlike self-publishing, where the use of external professional services for parts of or even the entire publishing process is normal, with the "do-it-yourself" publishing this is rather an exception. The budget of the author in the latter case is much smaller and payouts are reduced to the possible minimum.
"Do-it-yourself" publishing and the Internet
The financial demands on the self-publishing author have become even lower with the advent of the Internet. With today's widespread computer literacy many computer users are perfectly capable of producing good quality electronic books themselves. With computer readable books and the Internet the reproduction costs, which were the major obstacle to the self-publisher, become practically insiginificant. And most of all, with the use of the Internet the global market is practically at the fingertips of the self-publisher.