how to make a pdf file disable the save as function but print

I need for a project to be able to post pdf files that

- cannot be saved by the customer on a disk or harddrive
- can be read, viewed by the customer

Now all I have read on the net is that this not possible - but the idea is to make it as hard as
possible - I know the screenshot function.

Simply let me know if you:

Customer can view, print but not save. HOW to achieve this result

Could you tell me how to disable the SAVE AS function but customer can print ?

Are you aware of any reasonable priced DMR that could achieve this or able

to do this for me ?

Thanks a lot !

Any ideas of how to achieve that result with deiiffernet means ???