New trends forcing the attractiveness of products in sustainable processing make it necessary to search for innovative methods of measuring their quality. For various biological materials, their physical properties, such as friction parameters in addition to their texture, are very important. Friction determines the course of many technological operations, e.g., transport, cleaning, sorting, fractionation, storage, and dosing of materials. An innovative friction adapter was developed for biological raw materials and tested on samples of self-produced soap. A 3D printing method for the production of this attachment was used. The soap sample loads were 100, 200, and 500 g, and the measurements of frictional resistance were carried out in contact with dry or water moistened synthetic leather, in comparison with sandpaper. For all tested variants (surfaces × loads), the initial friction of soap ranged from 0.853 N to 5.316 N, dynamic friction from 0.123 N to 3.542 N. The static and dynamic friction coefficients ranged from 0.019 to 0.151 and 0.006 to 0.131, respectively. The developed adapter for testing the friction coefficient ensures easy and quick assembly of the analyzed sample, its quick exchange and stable operation in both measurement directions, i.e., pushing and pulling the sample, as well as the possibility of using a lower applied load.