Good job Cupie. 

My work years back included exposure to intellectual property law. Copyright is a very complicated issue and is much broader than many understand, and I am no expert.

This is an excellent resource if you have a question and it is pretty easy to understand .... Home - Australian Copyright Council

You do not have to register copyright. It simply exists to protect any and all original works. Only the copyright owner can determine where or how a work is used or release it for public use.

And if you purchase an original artwork (for instance), you own the original, but the artist still owns the copyright. So it is possible your clay figurine copyright is still owned by whoever made it first and taking a photo of it would breach that copyright, but I doubt you will have a problem. There are exemptions for certain copies for certain uses.

Also, having something displayed publicly (like on social media) does NOT mean that the copyright is null and void. Like parking your car in the street does not mean that anyone can use it.

Copyright can be worth a lot of money, and having something released to the public to use often comes with restrictions. This is an example. The Aboriginal flag copyright was purchased by the Government from Harold Thomas for $20million so that the public can freely use it on cloths and web sites for example, but flags must be purchased from one specific company.

aboriginal flag copyright - Google Search

Breaching someone's copyright can get you into deep legal trouble. 

Take care.

Cheers,

Peter