Here are a few pointers for exporting STL files for 3D printing, regardless which 3D CAD software you use to create the 3D models.
(1) Overall model needs to be watertight. There should be no holes or floating mesh anywhere in the model.
(2) Any intersecting solids need to be merged together, either using Boolean Union or Solid Addition function, to form one big block of solid. 3D printers do not like intersecting solids because they see them as separate entities.
(3) Minimum thickness that can be printed is 1mm. If the part is smaller than 1mm, then they'll need to be sized up or inflated to more than 1mm for the 3D printers to recoganise as a printable part.
(4) Save different parts as separate STL files before exporting them.
We can provide a preliminary 3D model inspection to let you know if your models are 3D printable. We'll give you feedback on how to fix the models on your end.
We charge $100 + GST per hour to repair the models for you if you need assistance.