Creating asset bundles realtime

Hi Guys, I am developing an application in which users have .stl file, application parses data and create mesh from it, users can save it in their local directory and share with friends. Now I need to add some features in it for example, allowing user to change textures, colors, to combine multiples meshes, to add audio files and some other ideas. For that I assume I need to write my own file format which will include complete detail of gameobject i.e meshes, textures, morphing data, transformations, audio files etc.

I would like to ask that is there anything similar to asset bundles in unity which I can use to save complete data created in 'runtime'. Any suggestions regarding it ? My initial thoughts are to create a simple text file and start with adding and reading mesh data in/from it.