Tell us about yourself!
@jacobyGoosey. The cinder blocks used in this instructable are 16" in length. It warms my heart to hear that your working on a project with your great grandma. I hope your projects turn out to be both beautiful and bountiful! If you have any other questions, feel free to ask away, I will do my best to help. Good luck with everything!RollinCaswell
How to build a Rocket Mass Heater