Surgery often results in uncomfortable arm and upper body postures, placing high strain on the upper extremities and leading to musculoskeletal disorders, which can impact precision tasks. A surgical arm assistance system physically relieves the upper extremities during surgical procedures, by actively supporting the forearms. Research shows an advantage of a percentile-adapted anthropomorphic forearm support shape over a flat forearm support and over no forearm support. Within this research paper, nine material combinations consisting of three surface materials (medical synthetic leather, neoprene, sterile foil) and three padding materials (solid gel, neoprene, foam) are being analysed in two differently sized anthropomorphic forearm support shapes and a flat shape. 31 test subjects perform randomised dynamic and static precision tasks with and without surgical gown using the material and shape combinations. In the dynamic task execution the most errors occur with the surface material sterile foil. The lowest average number of errors occurs with medical synthetic leather as the surface. In combination with the three surface materials, the lowest number of errors occurs with the padding material solid gel, followed by foam and neoprene. The best comfort rating (7-point bipolar Likert scale) occurs in the combination of neoprene surface and solid gel padding. The results of the statistical analysis of the test parameters are used to derive surface and padding material recommendations for the design of a forearm support shape for the interaction with arm assistance systems.