MABEL

What the build sources contain

The archive includes STL parts and files named MABEL.step and MABEL.f3z, plus a README BOM and five illustrated mechanical assembly stages. The CAD files have not been opened or checked for assembly completeness in this review. Those stages cover bearings, servo installation, gears, stepper motors and joining the leg sections. The BOM names a Raspberry Pi Zero W, Arduino Uno, two NEMA17 steppers, six MG996R servos, stepper drivers and an MPU-6050. Four servos appear in the described leg assembly, so the full BOM count should not be confused with the four leg-control angles. [S001] [S004] [S009]

The electronics construction section is still a placeholder. The README also spells the servo controller as PCA9865 while linking to Adafruit ServoKit guidance; the exact board needs reconciliation with the selected hardware rather than silently correcting the document into an assumed specification. Its battery and regulator list is not a verified wiring or power design. No current complete delivered cost is established. [S001]

An inverse-kinematics example is not the full controller

IKDemo.py reads requested coordinates, calls IKSolve and prints the returned angles. It does not itself command the servos. The README discusses optional input libraries and says controller code remains under development, so a builder still needs to complete that integration. [S001] [S007] [S008]

The home angles in the example are explicitly build-specific. The supplied balance sketch likewise contains accelerometer calibration and PID parameters; copying those values is not evidence that another assembly is calibrated. No servo motion, sensor setup, balance test or terrain experiment was performed here. [S001] [S005] [S007]

Source rights and completeness

The root repository contains GPL version 3 text. The balancing sketches derive from YABR according to the README and carry an embedded warranty disclaimer; this review has not fully resolved the inherited-source license chain. A disclaimer alone should not be treated as a complete reuse license. Purchased electronics and independent libraries also remain outside a blanket repository-license claim. [S001] [S003] [S005] [S006]

The practical distinction is between a documented mechanical starting point and a fully commissioned balancing robot. The first is present; the second requires electronics completion, controller integration and build-specific calibration beyond the evidence established here. [S001] [S007]