Hmm. There's a Photoshop plugin that adds a puzzle piece outline on top of an image - forgot the name. But you could apply the filter to a blank (white) square, export the resulting image and make a 3d extrusion out of it. It's the Supermesh function in Raydream, I assume it's still around in Carrerra. Then export the whole thing to obj, after grouping, etc. Might be faster?