BookMaker is a tool that runs in your browser that helps you to easily create and edit collections of pages for export. You can currently export from Wikisource as ePub, as well, less reliably, as PDF, ODT and Zim.

To use the BookMaker tool, activate the gadget in your preferences. The "Create a Book" link in the sidebar will change from leading to the PediaPress tool (which is not generally suitable for Wikisource works), to triggering the BookMaker tool, which appears at the top of the page that you are editing.
When the tool is active, you will see two areas. The left-hand area is the "pending" list, and the right-hand area is the "existing" list. You can add pages to the pending list by clicking one of the buttons:
  • This page add only the current page
  • From links on this page adds the links that are found in the body of that page, in order. This is useful when that page has a table of contents.
  • From subpages of this page finds the subpages of the current page and adds them to the list. The order is not guaranteed to be correct.
  • From saved version of this book loads the pages from the saved version of the current book, if it exists. It is disabled otherwise.
  • From a saved book... invokes a dialog box that asks to enter the name of a saved book. Pages will be added in order from this book.
  • Another page... invokes a dialog to enter the name of a page to add to the list.
  • From a category... adds pages from a given category.
Both the pending and existing page lists can be manipulated in several ways. Firstly, you can drag to re-order the pages. You can delete a page by clicking the icon or ctrl-clicking the item in the list. Pressing [Clear all] above either list will delete all the pages in that list

Additionally, you can proceed to view each page by clicking the icon.

Whenever you change the book, the border of the BookMaker will glow green. This means that the book has been saved temporarily. You can navigate to another Wikisource page and the book will appear there as well. If you close the BookMaker, the book will be lost. If you minimise it, it will be kept, and the BookMaker will appear minimised if you change pages.

You can then move the pages from the "pending" list to the "existing" list by either dragging them across individually, double clicking, or by clicking the ">>" button, which moves all pages across. You can move pages back by the same method.
To "tag" a page as the source of this books metadata (so you don't need to replicate the data on the book page and expose it to possible divergence from the book), click the icon. The currently tagged page (if any) will be bolded and show a red icon. You can tag only one page - if you tag another, the first one will become untagged.
If there is no existing Wikisource page which has the metadata for your book (for example, if you have made a compiled book using extracts from multiple Wikisource works), you can tick the "Use manual metadata" box to enable the text fields. You can type your metadata in directly, or "speed-load" whatever metadata is on the current page. If you use manual metadata, any currently tagged page will lose its tagged status.
To save the book, click the "Save book" button at the bottom. If there is no metadata (either a tagged page or manually entered), you will be warned. If a book exists in the specified location, you will be told who last edited it and when, and you can choose to save over it. When the book is successfully saved, you will be taken to the new book page that you just created.