Summary

Simple Sponge Filament Filter for the Makerbot Replicator 2

Instructions

Print the Cap, Body, and Guide Tube
Glue the guide tube to the bottom of the body (CA glue)
Cut a 1cm cube from a kitchen sponge
cut a slit in the cube to allow the filament through (from any edge to the center)
insert the sponge into the cavity in the body
screw cap onto body (I used hex cap M3 8mm screws)

NOTE:
I added a some painters tape to the outside of the guide tube to allow for a snug fit into the extruder.

I also uploaded the Inventer Fusion files so feel free to change the design to fit your needs.