Spool Core for 3/4 PVC Pipe Holder

This is a down and dirty remix of the Resizable Loose Filament Spool
by shaunp, published Mar 17, 2013. It is a modification to the "LFS_Hub_External_30mm_V3.0.stl" file which allows nice fitment to 3/4" PVC spool holder. This helps facilitate better motion on an cheap home made spool holder when dealing with air spooled filament (personally hate it).