What do I have here?

I recently bought a box of old photo accessories. I have already identified a few things but others still have me scratching my head.

An album with descriptions can be found here.

If it is of any help, other things in the box were branded Pentacon, Balda, Leitz, Kiev, Ihagee, Zeiss Jena, Busch (and others).

Edit: The round silver part in picture 3 fits the spool of a 35mm canister - I suppose it's for using 135 film in a 120 camera.