mesh problem

[aandrz]

Hi, I am having a lot of problems with a mesh. I want to make a completely solid transducer so I can make a negative of it to make a transducer holder. 

However, after doing repair, erase and fill, generate face groups, and validate actions, I am still not able to get a solid file that I can use to make a negative.

After converting the presumably faulty mesh to a solid, I get errors like:

"There was a problem combining geometry together.  If
attempting a Join/Cut/Intersect, try to ensure that the bodies
have a clear overlap (problems can occur where faces and
edges are nearly coincident). "

or 

coincident intersection edge previously non-coincident"

If anyone can help that would be much appreciated, I have attached the file.

[JeromeBriot]

Repair the mesh first using Meshmixer :

1. Install and run Meshmixer
2. Go to Analysis > Inspector > Auto Repair All
3. Go to Edit > Make Solid, select Sharp Edge Preserve for Solid Type and click on Update then on Accept
4. Select all the triangles by clicking on one triangle and then pressing "E"
5. Press Shift+R to open the Reduce tool and reduce first by 90% then by 50% (number of triangles should be less than 10000 now)
6. Export the repaired mesh as STL

Now you can import and convert the mesh in Fusion 360.

[TrippyLighting]

I think  to create a fully solid model of just the exterior, you need to remove all the interior faces or face groups and then fill the holes. That is likely better done in Meshmixer and then should create a watertight mesh that can convert into a solid body in Fusion 360.