Packt Publishing is currently offering free ebooks as part of Android Week 2016. This is a nice opportunity to grab free books authored by reputed authors on a wide range of subjects.
As of this writing, Android 5 Programming by Example is available for free but not yet available for users. However, another book titled 3D Printing with SketchUp is available for adding to your account.
To claim a book, you need to login and select Claim Your Free eBook button. The book will be added to your account. You can either download the book in PDF format and add them to your Kindle account by providing your Kindle email.
To recall, Packt Publishing has given out free ebooks in the past as well.