If you are looking for the software itself or documentation on how to use it, the most prominent tools in the hobbyist community include: VXP Builder / MRE SDK: The official developer tools for creating VXP files. MythRoad/MRE Compilers:
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The short answer is . There is no official or stable "automated" software that takes a .jar file and spits out a working .vxp file. If you are looking for the software itself