Hi

Is is possible for manufacturer to create their own product?

Administrator creates manufacturer and assigns product categories.

Manufacturer uploads his own proucts.

Either via access right or specialist module?

Hi,

You should try forum.virtuemart.net for this inquiry.Because this is directly related to Virtumeart Core.
We don't provide free support if the inquiry is not related to our products.

FYI: If you give enough access level to manufacturers, then yes, it will be possible. But you should give them "joomla administrator" access level though, which is little risky though.

Check this topic: forum.virtuemart.net/index.php?topic=111446.0
this might work for you.