Hello, now I want to make my own assembly joint dataset, and use the model in Joinable to assemble into a two-fingered manipulator. I find that there is a json file for each part in the dataset, and another joint json file after they are assembled, there will be 3 json files in total. If I just want to apply the joinable model for assembly, how do I get or make these json files that similar to those in the assembly joint dataset