Beto : What you are suggesting is exactly how I thought I would be proceeding with my larger models- larger pieces in cheaper "White Strong & Flexible", smaller detail parts in "Frosted Detail". The snag is that WSF is no longer the cheaper option: For a start, Shapeways charge a handling fee per component in WSF whereas in FD they will accept almost any number of pieces in a model for a single handling charge, plus the material cost (have a look in my shop at the HTA - Heavier Than Air - unit for my Akron and Macon for example or at my military vehicle sets). Secondly, WSF will print at a minimum wall thickness of 0.7mm whereas for FD it is only 0.3mm so the material volume in WSF is much higher than in FD. Finally Shapeways penalise a design if it is hollow in such a way that they cannot print other items within that space. So for example, my WSF R101 and R100 both started life as beautiful one piece hollow prints. Shapeways then changed their pricing formula to include something they call "machine space" and the price of both models doubled over night. The only way I could keep them at anything like a reasonable price was by splitting the models, which was very sad because it rather destroys one of the major benefits in 3D printing - i.e. very complex shapes in one piece.
So the end result is that WSF actually ends up as MORE expensive for my models than the FD alternative. Believe me, with every design I work on I check out the material options to ensure that I am offering the models at the best possible price. The fact is though, that more of my models would be in FD and at lower cost except for the fact that Shapeways FD printers are not big enough! The greatest sadness for me is that despite all the hype about 3D printing over the last few years, prices have risen dramatically instead of coming down! This is a criticism of Shapeways BUT, they are the most competitive in the market and their contactability and after sales service is, I believe, second to none. They have been investing constantly in improving their software systems and in offering new materials. They are the market leaders and that is why I stick with them.
I apologise for such a lengthy reply but the whole issue of price is very close to my heart - I want more people to enjoy my models but I know that many are simply put off by the prices I have to charge. Having said that, most of my models are not available anywhere else and one could argue that the prices are reasonable considering how exclusive the models are.
Thanks for raising the issue Beto;
Derek