Seems things are priced as if the model is a solid chunk of material based on footprint volume, rather than an open top box type part that mates with another. It would make sense that powdered material could be shaken off and re-used if it's not trapped in any way, however it doesn't seem to be accounted for. So I end up with a product that costs 10X than what it should given the relatively thin wall thickness and perhaps a reasonable time to process in a machine. (Current pricing is over $100 for something where I'm only putting $5 on markup. Maybe corporations don't care about things like this when prototyping - eat the cost and write it off as part of business, but to an average person such seems ridiculous and out of reach.) Outside of that, any way to just sell a download of the model itself? I see making the model downloadable for customization, and I figure a person could do an FDM print at a much more reasonable cost than SLA. And it would be reasonable the site would still get some cut of the fee for hosting it. But it's not clear if you can charge for the model's file in itself.
How big is the object? In Versatile Plastic, an open void must have a 40mm or larger hole to the outside, or it's considered to be a solid piece. There's no provision at this time for selling models for download.
If the model has to be articulated to access the interior, It seems unlikely the software examining the model to set a price would account for that. If the clam shell opens to a full 180 degrees, uploading the model in that configuration may help the software figure out the hollow.