BMW AG has given 3D printed thumb guards to workers in one of its German factories to relive strain on their hands, which comes from assembling scores of vehicles daily.

The "super thumbs" were designed by the Technical University of Munich's Department of Ergonomics specifically to fit each worker's thumb, according to The Independent. They act as a split to strengthen the joint when workers push in rubber holding plugs.

The 3D models were created by scanning the hands of the workers from every angle. The models were then used to create a 3D-printed plastic protector.

Thermoplastic polyurethane (TPU) was used to make the thumbs. TPU is limp and floppy in its natural state, but is elastic, allowing for it to be processed to form a splint, The Inquirer reported.

Car production lines have many jobs that involve manually pushing rubber plugs and other insertions into holes in the car's bodywork. Unnecessary strain on thumb joints can be caused by tension of fitting material in the holes.

"There are many things that can cause stress like this, including posture and the number of times they do a task," said Prof. Peter Buckle, head of the Robens Center of Health Ergonomics at the University of Surrey.

The semi-flexible plastic material in the thumbs helps joints move freely most of the time. However, the joints are also able to become rigid when straightened, which allows workers press down with less strain, The Independent reported.

"Even for people with strong hand muscles, the movement requires a certain effort," said a BMW spokesperson.

The German automaker said it will hold small trails that, if successful, would allow them introduce other projects involve the use of 3D-printed equipment to keep workers from experiencing strain and injuries.