I attempted to open the tantillus stl file for top corner front left but sadly it failed in lic3r saying it had no slices or something, and Bill20r3 and teepee on IRC #Reprap explained about Admesh program.

A commad bassed programme, it fixes / translates rotates etc stl files.

to download:
bill20r3> admesh seems to have fixed it just fine, fwiw.
admesh?
admesh is an open source program for repairing, translating and processing STL meshes. It’s very fast and almost as old as 3D printing. https://sites.google.com/a/varlog.com/www/admesh-htm

if this is down due to server issues go to:
http://ftp.de.debian.org/debian/pool/main/a/admesh/
and download
admesh_0.95.orig.tar.gz 12-Oct-1998 20:52 50K file.

Roboteernat: bottom of the page https://sites.google.com/a/varlog.com/www/admesh-htm – the small arrow pointing down

download the file and save to desktop.

open command prompt window and change directory to point to admesh folder

save the broken stl file needed t be fixed ithin the admesh folder and confirm it id there by using cmd window and typing 'dir' to list the files in the directory

Once it is there, we can fx it.

Type

admesh --write-binary-stl=file_admesh.stl file.stl

where file_admesh.stl is the file output name
and file.stl is the name of the file to be fixed

Here is an example print screened for the future 🙂

the file ‘Corner_top_front_left(1).stl has been fixed and saved as Top_corner.stl in the admesh folder.

All slicing fine now 😀