Is there a paper wallet for all crypto-currencies? I am relatively new to crypto-currencies and I am just wondering if there is inherently a paper wallet for all crypto-currencies made?
Do they all have public and private keys that you can write down on a piece of paper to store?

The reason I ask is because I am looking into diversifying my portfolio and I have my eye on some coins but I cannot confirm that they have paper wallets.
An example: MaidSafeCoin can be kept on Bitcoin address. There are a lot of ways to store bitcoin addresses. Paper wallet being one of them. So MaidSafeCoin can be stored on paper.

If all coins use public/private then it is just a matter of writing those down. Am I missing something?
Essentially yes. Paper wallets are just storing the private key in written format, and you can encode just about any data into a QR code. The limitations to this would be centralized alternative coins where users are unable to hold their own keys.