hi, i'm new with mujoco and i don't understand how to import and visualize a XML model file with mujoco-py, can someone help me?
Please read the documentation, and study the code samples and models available in the software distribution and under Resources on the forum. Then, if you have specific questions which you are not able to answer for yourself, post them here. If you are using the Python wrapper, note that it is developed by OpenAI so python-related questions should be posted on their forum. As for building 3D models (which is MuJoCo-specific and not related to python), start by reading this chapter in the documentation: http://www.mujoco.org/book/modeling.html
MJCF models are built by hand in a text editor, similar to URDF and SDF models. The modeling language is too rich for a visual editor.