It took at least 3 or 4 minutes to render, much slower than any others I’ve done. That was at a threshold of 64. The stats say that there are already 78k triangles. The example file, which includes a USB port, has 55k. So I’ve managed to add almost 50% more triangles. I suspect the fact that I made the inner section solid is where those triangles come from – the holes have depth, so every one of them is adding quite a few triangles. Though most aren’t going to be hit by the ray tracer.