Hi!
I would like to share a simple add-on I’ve made to hollow out meshes for 3D printing. I’ve posted about it in the devtalk blender forum. @Okidoki suggested I should also post it here, so there 
The add-on is available here (github). It is a single .py file with less than 200 lines.
It uses pyopenvdb that is distributed with blender since 3.5.
Some results
Here is an example with Suzanne. The result was cut to show the hollowed out inside of the model.
As arguments, the add-on takes the desired offset, the resolution of the level set and a boolean to indicate if the created surface should be joined with the target.