Here is my "dungeon door" test mesh that I use instead of teapots. It was really easy to convert an .obj to JSON format in the end; I didn't need to use an exporter or a Python script, I just re-used my C .obj parser code and got it to write all the vertex points to a JSON file. Excellent. I'll upload the programme when it's a little more fully-featured. Now...textures.
Perhaps some Phong lighting shaders using normals. I also need to think about refactoring these demos into a semi-stable engine where I can re-use the data-structures for many objects/textures/matrices at once. Some manager objects will probably be required. Maybe I should look at extension loading as well.