Design Patters for Hardware Security Module Interface application

I have PKCS11 wrapper DLL for .Net, written in C# . I want to use the DLL to write Win Forms Application having the functionality of key generation, key loading, encryption, decryption, etc., in fact all the functionality of a Hardware Security Module does. The coding involves opening a session or multiple session, involving various operation.

Could anyone suggest which design pattern should be perfect to write Windows form application? In future, this windows application should be integrated with payment card industry for various purposes.