Blender at least a little bit because that's covered in the previous chapters. Owning a 3D printer is not necessary. In return for your services you will receive one physical copy of the finished book and your name in the credits of the book. As an additional incentive, if you sign up for this and stay through to the end I will send you a RoboAction Chess set for participating.
If you are interested you can contact me on my other website by following the link below and I will put you in contact with the Packt people:
Per Joseph Chiu I better mention that we're talking about about 3-4 hours of your time that can be spread out over several nights. Could be done with this in a week. That's my time estimate based on my personal estimates but the publisher may be able to tell you better.