To be able to update public inventions.
This could go like this:
There would be a button when purchasing or downloading an invention that said “select invention version" and you could pick which version of the invention you want to download, and it would download that version. Each version could have a different name (like a version number) and it’s own thumbnail. It’s really annoying having to unpublish an invention to update it and then lose all the cheers and downloads.