If you have a complex model in mind, once you learn how to use Blender it’s way more time efficient and will give you a much more customizable result if you build it from scratch with Blender tools rather than using Roblox to make meshes.
If you don’t want to learn Blender, you can use the “Export Selection” after right clicking your model then import it with the Asset Manager. You can use this plugin alongside the Studio exporter to retain your color/material groups. Though, this might not be what you’re looking for since this method won’t end with a single mesh. The plugin will sort the models into groups so they can be exported and reimported as separate meshes. This is basically the same solution @okayendo gave but using a plugin to group the objects rather than splitting them in blender. You may end up needing to use blender if there is weird geometry that needs to be cleaned up or if you have to reduce the triangle count before importing it back into Studio. If you are working with models with extreme details, it’s only going to increase your triangle count. (Again, it’s a lot easier to fix meshes made within blender rather than fix up exports from Studio)
With this method you can clear the mesh textures and use custom materials/colors from Studio if you want to change it’s appearance down the line. It’s a lot easier and more adaptable to create a texture through the Material Manager for general mesh use rather than mapping textures specific to each mesh, in my opinion.
This is how a model would look separated:
Sorting and Exporting a Model:
After Importing Each Mesh:
Make sure “Import file as a Single Mesh” is checked when importing, otherwise the import tool can sometimes recognize the .obj as multiple splits if you didn’t group them in Blender and you can accidentally end up importing every part as an individual mesh.