Here is an idea for an economical thin shell, inflatable form work (for sprayed thin shell cements), using one sheet, (just as it comes from the factory without job site modifications), to build those NURBS surfaces you are dreaming about. Otherwise, it is a good starting point for designing a rigid framework for tensioning translucent skins. (I'm interested enough now to model such structures based on what I learned with this new model). Today's considerable green house plastics are gradually improving and the sizes cover needed spans, which are easily erected and easily replaced after (the current) lifespan of 7 years, which also depends on location and budgeting, (the point being that costs are more reasonable for such skins as compared with high end projects).
More details and pics are here: http://harmoniouspalette.com/MonolithicSheetDomeStudy.html
In case examples of my building experience are of interest, here are structures I have built (albeit on shoestrings, so naturally there is no polish).