May I ask why? Is it of inconvenient size, do you not like to carry baggage that you do not need most of the time or is it just that you do not want to be easily identifiable most of the time?
The German "Personalausweis" (official id card, distinct from passports) is sized and shaped like a credit card and therefore easily goes into the wallet. We used to have larger ones in the past which indeed did not fit into some wallets. It is also very convenient to have it on you to be able to identify yourself in whatever situation.