I made a new Design Rules for Stainless Steel tutorial for you. This tutorial should help you guys tackle the issue of designing for Stainless Steel 3D printing. I basically used the Glass Design rules tutorial as a starting point and was able to recycle all the images in that along with some text. This should give you an idea how similar the processes are. They are however different, more is possible with Steel. I like for this to be a "living document" and update it with new feedback from production or you. So please either email, comment, or write in the forum if you think new things need to be explained. I hope you find the new tutorial useful.
The main issue that we are seeing right now are moving parts. This causes a lot of Stainless Steel models to fail. We are cognizant of the fact that we would love to be able to tell you upon upload if a model will work or not. Our automated filters have come a long way, especially with the recent introduction of Mesh Medic. However we still are not able to always tell you in advance if a model will print or not. With the thermoplastic 3D printing processes we are further along then with steel and glass. This is partially because the Steel and Glass processes are so new that they and their design rules are evolving. Another reason is that these processes themselves are much more complex.
The moving parts issue is one such issue. Moving parts are possible but I would discourage them. If you do want to do any kind of moving or loose part a 10mm gap between both loose parts is necessary. Any loose part can not be longer than 80mm. Even then your part might fail.
With regards to these rules, Cooldjez's great ring, pictured above was posted on the forum with "defying the steel rules" and indeed it does. We can still print it but we did not anticipate being able to do so ahead of time. We would love for our design rules to be set in stone. We know this will be much easier for all of us. Indeed, its no fun having to tell people that their design is not printable. We hope you guys understand that all this is very new and things change.