I understand that this is a substitution, but the introduction of 44 new symbols is inconvenient for users. 
In fact, I currently use a credit card-sized metal card, with a one-to-many substitution table on the card face, and then switch the substitution set through the rules I define, as long as the rules are kept secret, your plaintext will be safe no matter the ciphertext is displayed publicly, or the card face and ciphertext are displayed at the same time. FYI.