I'm creating a model at the moment, still working on the design. I've uploaded a copy which is about 10cm on it's longest axis.

The cost for the model at 10cm is $ 14.70 WSF, $ 10.21 for sandstone. Which intuitively is correct, because sandstone costs 2/3 for materials, plus the surcharge to start with.

However, if I upscale exactly the same model to 20cm, using the same blender file and exporting it out the cost comparison changes.

The cost for the 20cm model is $ 69.24 WSF, and $ 71.12 for sandstone.

Is there a cost to exceeding a certain scale in sandstone?

I thought sandstone was recommended only for larger scale models?

Or is it a bug in the calculation?

Sandstone should be around $45, assuming the WSF estimate is correct.