I released version 0.3 of Mark Book Builder. You can download it from this site’s homepage.
The new feature in version 0.3 is basic support for images. To add an image in a chapter, click in the text view where you want the image to appear. Choose Tags > Image. An Open panel appears. Select the image file you want to add. Click the Open button. An image will look like similar to the following the text:

If you want to insert some alternate text, enter it inside the square brackets. The ../Images
before the name of the image file ensures the image file appears properly in the EPUB book.
Currently the image support is basic. You can add images to books. If you need to remove an image, you must both remove the image tag from the text view and remove the image file from inside the book. To remove the image file from the book.
- Select the book in the Finder.
- Control-click, hold down the Control key and click the mouse or trackpad.
- Choose Show Package Contents from the menu that opens.
- Double-click the Images folder.
- Select the image file you want to remove.
- Move the image file to the Trash.
The Images folder contains references to the actual files on your Mac. Moving one of the files in the Images folder to the Trash will not delete the actual image file.