A holder for filaments with a small central hole that attaches onto the back of the Makerbot Replicator 2 as you can see.

Used for filaments such as this - http://uk.rs-online.com/web/p/3d-printing-materials/8320416/

Designed in DesignSpark Mechanical - file is attached.

Dowload DesignSpark Mechanical - http://www.rs-online.com/designspark/electronics/eng/page/mechanical

Print vertical with supports and rafts.
Works well with 0.2mm resolution.