Prerequisite to building a Rhino plugin, I need to validate my understanding of the sketchfab upload process. I begin with a python script from the API page, my new token and a sample lamp OBJ file.

type in ‘pythonw upload.py’ and a successful upload delivers a screen dump of the file transfer along with an id and validating success confirmation.
My credential works and now I am ready to write my own uploader test in C#. From the API and python script, I gather the four necessary steps; 1) load CAD file, 2) convert to base64, 3) build JSON, 4) upload/post JSON.
Rhino v4 supports plugin development with Visual Studio 2008, C#, VB and C++. The simplest for me is a C# dialog application with default controls and OpenFileDialog module.
Using FileStream, CAD file is read in as a byte array.
Since some CAD files (STL, PLY) can be in binary or ASCII format, a base64 conversion is used. Thanks to C#, the conversion is available in the System.Convert library.
Following Sketchfab API, I am creating a JSON string with below function. After conversion to a byte array, HttpWebRequest uploads my content to sketchfab server.
Upon a successful upload, I receive a confirmation id and ‘success : true’.

It is exciting working on my first Rhino plugin with C#, Visual Studio 2008. The body of code samples is massive (over 150+). From McNeel’s dialog example, I am able to incorporate the test code user interface.
The challenge is getting access to the mesh data. It seems that each example requires user to select data and I am at a loss how. Might you share some wisdom ? Here is my source code for ExporterTest and RhinoExporter (experiment).

Happy to have found the most recent Rhino 5 API documentation online.