If you make it database you can't open it with anything else than your own loader, is possibly larger and slower to open.

On current day modellers use all same programs like 3DS Max or Lightwave etc. That defines what file formats programmers need to use, and it's not a bad thing really, lots of thought have put into their design.

I went using my own text format but also OBJ and little bit Milkshape3D is supported. Most people use 3DS, MD2 or MD3 format but you can expect to study a bit to learn them.

Lines? There is no such thing in 3D model. Vertices, polygons, texture coordinates, normals, possibly color materials, animation frames and bones.