I understand from reading these forums that Shapeways maintains a flag on each version of each design that says that the design has printed successfully in the past. On the face of it, this seems like a wonderful idea, because it should give the designer some confidence that -- after ordering a successful test print for himself or herself -- that customers who subsequently order the same print will not get the dreaded "Could Not Be Printed" message. Such messages are an embarrassment to the designer and a hassle and potential cost to the customer, should they have to pay additional shipping to re-fill the failed part of their order.
However, it's not working out that way...in fact it's having the opposite effect. I'll explain, from my perspective...
I (and others, judging by the threads) have seen a lot of cases where designs that have successfully printed before are later rejected. I understand the reasons, and several times there are places where I pushed the tolerances too far and corrections should be made. (Scale modelers tend to really want to push the limits to keep things proportional.) I'm not here to debate that...there are other threads on the subject.
But in practice, the has-been-printed flag is doing nothing to reassure me that a design that printed once, or even twice or three times, won't be rejected tomorrow. It happens too frequently.
On the other side, I'm reluctant to change any design for which the flag has been set, because it will mean that my model will be subject to increased scrutiny the next time it is printed. In fact, to be a responsible designer, I almost feel like I should pull a design off the market every time I make a change -- even if it's one that I know will make the model more printable -- until I've had a chance to order the revised copy and be sure it can print at least once. Because, while I may have fixed a printability problem on the left side of the model, there might be something found on the right side during the "increased scrutiny, because it's never printed before" check.
So the has-been-printed flag actually forces me to think twice about changing any previously-printed design, even in areas I know are "iffy".
So.. in a strange way... a concept that should be making me feel more confident about my model's ability to print is doing nothing for my confidence, while making me reluctant to fix known problems.