The Brick Castle: Discovery Mindblown Hydraulic Robot Arm (age 10+) Review (sent by The Essential One).
Amazon.com: Make a working wooden Robotic Arm Kit | Learn about fluid dynamics | facts and easy instructions included | Copernicus Toys Curious Engineer Kit : Arts, Crafts & Sewing
STEM toy review: hydraulic robot arm – janjanjan
PDF) Hydraulic-Powered Robotic Arm from Simple Materials for Engineering Education