Physical wallets in coin form dates back to 2011, when Mike Caldwell started manufacturing of metallic Casascius coins which contained a Bitcoin private key under a security hologram.
After Casascius, other have begun their own production of coin formed Bitcoin wallets. A variety of security solutions to protect the private key is presented.
Bitcoin coin manufacturers:
Alitin Mint Antana Casascius CoinedBits Cryptmint Denarium Ravenbit Satori Titan Bitcoin
Paperwallet is a term which refers to all kind of materials and becomes from the idea that the private key is printed or written in the paper. It has become a general term, but it can refer in particular to the bank note like bills, which can be seen as kind of a paper money. If private key is visible it can be protected with password. Term cold wallet is another way to express that the private key is stored offline.
Hardware wallets include a lot of devices like Ledger wallet and Trezor. Depending on the type of the hardware wallet it can be used together or separately with the digital Bitcoin wallet. It can play a big role in preventing unauthorized transactions and some of them are capable to store and send bitcoins itself, without outer devices.
Purchasing physical wallets usually requires trust to the manufacturer. Self-made physical wallets requires trust to the machines which are used to create the private key.
Physical Bitcoin coin manufacturer Denarium was first to introduce a multisignature physical Bitcoin wallets in coin form. The multisignature technology makes possible to create a trustless physical wallets. Thus, the manufacturer is not able to access funds under false pretenses.