How to generate a .png texture

Hi,

I am using Meshomatic to load an .obj model and attach a texture.
Until now, I can use the two examples ("cube.obj" with texture "cube.png", and "test.obj" with texture "test.png").

I would like to make the project work with other 3d models. But I have a problem with the texture.

I have seen on the web different tools that creates .obj and .mtl files, but none of them makes a texture like your "cube.png" and "test.png" files.

Can I ask you how did you make these .png files? Did you use any 3d tool to do it?

Thanks in advance.

Best regards,
_Sven_