A model I put up was given print runs in a couple material (WSF and FD) successfully. However, upon attempting to print it in WSF polished, the model was rejected for parts I thought were more like surface detail, hence why I didn't double measure them or make them thicker. In the image below, I can see that the top of the leg may be more of a wall, so that'd be my own fault. But surrounding the exhaust hole, I feel that is more of an emboss-and-engrave rather than a wall. So my question is, what is the distinction between detail and structure? I'd like to have as complete a checklist as I can before I order prints. It's not so bad at the moment since we're in the prototyping phase, but given the time it takes between being made aware of these issues and subsequently getting a printed prototype, getting it the first time would be nice.