Duplicator 4 OHSH OverHead Spool Holder

Remixed from http://www.thingiverse.com/thing:12974 as the Dup4 is close to the Replicator 1 but it varies enough to require a slight rework.

Revision 2 allows for easier attachment and better fitment with the added relief.

Removed older version and added new Sketchup source file. Also ran the file through Netfabb prior to uploading.