Make mesh surface a solid - Use Stamp?

I have an STL file of a mesh surface that I made in Blender. I would like to make the surface “thicker” and make it a solid.

I have tried to do this with the Stamp Tool, but I can’t get it to work right.



If the edges are straight you can just draw edges down from the corners and join the dots to create a skirt.
Or use one of various tools, vertex tools, extrude tools, skirt, toposhaper just to name a few.


I missed the Edit Group, Thanks for that.

I now have what looks to be a solid, but it needs to be a “manifold solid” to work with Slicer5, so I get an error.

How can I fix this?


I installed Solid Inspector2 and I get this error:

Nested Instances 1

It is not able to fix the error. How do I do it manually?


Nested means you either haven’t selected the group or you have a group within a group.