Deploying Custom Action Class When it is ready to deploy the solution, build your custom action project in release mode. Sign the assembly with a strong name key file. This ensures the assembly created can be deployed into Global Assembly Cache (GAC).You can deploy your assembly into the GAC by using the gacutil.exe that comes with the .NET Framework SDK. Here is the command: gacutil /i <DLLName>. Once the assembly is dropped into the GAC, your class is ready to use.