Convert STL file back to an NRRD format

Is it possible to convert an STL file back into an NDDR format so that, for example, the wall thickness can be adjusted again?

I know that you can save it as a lumen, but this takes a lot of time (Croped Volume).

If I only save the Croped Volume File, my segmentation is no longer available and only the original model is loaded. Saving everything takes what feels like 2 hours or more.

You convert a model to segmentation node by right-clicking on it in the Data module.

You can speed up saving by disabling Compression option in Save data window and buy getting more RAM and faster disk.

What node takes a long time to save? How large is it?