Puppets

In song.

The revolution will be harmonized!

This doesn't speak directly to your question, but in the appendix of the Neal Stevenson book, Cryptonomicron, there are instructions on how to use a deck of cards (technically 2) as a one time pad for encrypting and decrypting messages. This could serve as the foundation for secret messaging using other media than paper.

Defiant semaphore

Use them anyways.

Gratuitous acts of memery. Cats, Pikachu faces, swole doge and Cheems - you name it. Arcane to the uninitiated, ever so meaningful to the inner circle.

Learn to read people's minds, a la Pyre

Nah, fancy fountain pens are way too much of a status symbol to be outlawed. I'd just write with a montblanc - there's no way those filthy proles would be able to afford something like that, thus our interests as the capitalist ruling class are preserved!

Macaroni art

Goo goo ga ga

Helicopter dick patterns. Richard Code, if you will.

It's the only way.