How to hollow/shell a surface or solid with non planar edges?

Hi,

I’m trying to create a shell from an open surface which has none planar edges. See attached images for the form.
The final form will be 3D printed, which is why I need the none planar edges, as two halves will slot together guided by the irregular edges.

I have tried making the form solid and using ‘Shell’. I have also tried offsetting the surface but I get a lot of holes. As this is only one part of 100 I need to find a solution that does not involve exporting and importing (I have tried to use meshmixer also).

I appreciate any advice you can give me on this one, I seem to just be going in circles trying to solve this.

Edit: I have also tried to offset the surface as a solid, and again end up with holes.

If you post the file, you’re likely to get the help you need. :slight_smile: