Calling it a "snippet" is a great misnomer. The toolbox simply acts like a clipboard in this scenario. It stores bits of text, nothing more. It is automatable, you use the Toolbox interface in a VS add-in. They are stored in a ToolBoxTab named "Clipboard". It can only store 15 of them, doesn't scale at all. Really rather best to leave it to the programmer for his own use.
If you want to create snippets then do just that. Plenty of help around, like the Snippy snippet editor or this snippet designer add-in in the gallery. The MSDN walkthrough page is here.