i have found a pretty good idea which makes me a fair bit of cash!

i will not disclose the idea however, it involves an illegal document and fraud....i am scamming the buyer and pretending to be a goverment worker...

its made a good few $hundreds ...not major cash, but not bad....

Tldr:my question is if i am caught ...what kind of punishment would i face? I am 15 in Sydney if it helps..What can you tell me with such little information?

not alot, seeing as you are fifteen.

however from reading your posts I doubt you can pull this scam off sucessfully, so don't.