This is an application that uses Websocket to control Unity from Windows Forms. You can use Toolbox Control, which is not available by simply placing System.Windows.Forms.dll in Unity's plugins folder.
- Open "UnityForWindowsForms/App/" with Unity 2020.3.18f1 and build to "UnityForWindowsForms/bin/UnityApp".
- Open "UnityForWindowsForms/Forms/Forms.sln" with Visualstudio 2022 and release build.
- Run "UnityForWindowsForms/bin/Forms.exe".