Tesla is stumped on how to engineer this Optimus part, but they’re close

Tesla has been stumped on how to engineer one crucial part of the Optimus bot, but CEO Elon Musk says the company is “on the cusp” of achieving something great with the project.

During the Q3 2025 Earnings Call, Tesla CEO Elon Musk revealed the company is moving closer to a major breakthrough with the Optimus project, and said they are “on the cusp of something really tremendous.”

However, it seems there is one specific portion of the robot that has truly stumped engineers at the company: the hand, fingers, and forearm.

Musk went into great detail about how incredibly complex and amazing the human hand is, highlighting its dexterity and capability, as its ability to perform a wide variety of tasks is especially impressive:

“I don’t want to downplay the difficulty, but it’s an incredibly difficult thing, especially to create a hand that is as dexterous and capable as the human hand, which is incredible. The human hand is an incredible thing. The more you study the human hand, the more incredible you realize it is, and why you need four fingers and a thumb, why the fingers have certain degrees of freedom, why the various muscles are of different strengths, and fingers are of different lengths. It turns out that those are all there for a reason.”

It’s been pretty apparent that Tesla has made massive strides in the Optimus project, especially considering it has been able to walk down hills, learn things like Kung Fu, and even perform service tasks like serving food and drinks.

However, a recent look at a Gen 2.5 version of Optimus posted by Marc Benioff, the CEO of Salesforce, showed that Tesla was likely using mannequin hands until it developed something that was both useful and aesthetically pleasing:

Very likely that these are non-functional to not give away any major details about next-gen Optimus

The hands are amongst the most complex and important parts of the entire project https://t.co/YgoeNjamvI

— TESLARATI (@Teslarati) September 3, 2025

Musk continued on the call last night that the Tesla team was confronted with an “incredibly difficult” challenge from an engineering perspective, and the hands and actuators for that specific part were tough to figure out:

“Making the hand and forearm, because most of the actuators, just like the human hand, the muscles that control your hand are actually primarily in your forearm. The Optimus hand and forearm is an incredibly difficult engineering challenge. I’d say it’s more difficult than the rest of the robot from an electromechanical standpoint. The forearm and hand are more difficult than the entire rest of the robot. But really, in order to have a useful generalized robot, you do need an incredible hand.”

The CEO continued that developing a useful and effective robot was “crucial to the future of the company,” and that he works with Optimus’s design team each Friday night.

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