yes, we have done so for some customers who needed functionality like this. However, not based upon Oracle database 12C but on Oracle database 11G in combination with Oracle Enterprise Manager 12C en OVM.
The principle is quite easy however it will take a good base architecture of both your datacenter, network, storage, hardware and OEM12C as well as OVM and your templates. There is some balance you have to take into account. If you do a large number of deployements in a year or they are VERY time critical this is something you should look into. However, if you want to have it fully automated and self-service based you have to invest quite some time to do this in the correct way.... of you do not do that many deployments or they are not that time critical you can decide to keep doing this manually or semi-automated.
That is something you have to find out and think about and this should be part of your business case before launching something like this.
if you want to have a chat on this subject or do want more information, feel free to drop me an e-mail.