public static extern bool SetDefaultPrinter(string Name);

Declare Function SetDefaultPrinter Lib "winspool.drv" Alias "SetDefaultPrinterA" (ByVal pszPrinter As String) As Boolean

    result = SetDefaultPrinter(defaultPrinterName);

I tried this in a little test solution and now I have a magical method SetDefaultPrinter which you can use natively. There’s also methods for pretty much everything you can do to a Windows printer.