Mesh with Holes, Bionic Structure

Hey Guys,

I'm currently working on a project using bionic structures to reduce the weight of parts made by 3D printing.

Since my university doesn't teach Rhino or Grasshopper, I tried to learn the Software all by myself. Therefore, please don't be surprised about some basic stuff I don't know yet :-)

After baking the cube (with the bionic structure inside) I receive a 95% solid part. But by having a closer look at the surface of the component, some kind of graphical errors (kind of holes in the outter surface) can be recognized. For this reason, I'm not able to export the component into an STL. file.

Do you have any idea why these mistakes occure and how to fix it in the grasshopper algorithm?

Furthermore, I think about transforming this "shell-model" into a solid component. Is it enough to just bake it and export it as a STL file?

Thank you in advance!