Is there a way to combine multiple cloud storages into one virtual disk?

Question

Data storage

There are several cloud services for storing and synchronizing files (dropbox, google drive, Yandex disk, owncloud on VPS), each of which offers a small amount of data to store for free.
Is there a way to create one virtual disk distributed among these services and mount it into the system?
Something like a TrueCrypt container split into several files.

Answer 1

I use otixo .
It can work with almost all cloud storages and provide webdav access that can be mounted as a virtual disk to all operating systems without additional tools.

Answer 2

UnionFS?

Answer 3

mhddfs