I never dared to upload this thing before :-) but now... ehem... let's keep it like "I have my reasons".

Instead of using this thing, please do consider to use "real" bushings or any of the awesome other solutions already available in thingiverse (I do love this one: http://www.thingiverse.com/thing:4213 by twotimes)

For the curious ones, the stock bushings lasted the time to print less than 2lbs of plastic, may be I was not oiling them enough... These emergency ones have printed something close to 10lbs but I'm afraid that they start to ask to be replaced.

More pics? http://aubenc.imgur.com/bushings

(the picture where you can -almost not- see them assembled can be found here http://aubenc.imgur.com/cupcake_cnc_zextender)

The outer diameter I used is way to small so... wait to glue bushings and plywood until everything but the belts is in place. Also, use a little dab of "easy to remove" hot glue.

1. Print the stl of taste...
   1.1 - I did this thing before I knew that there was a cooling option in RepG, so I add the tube to help cooling).
   1.2 - There are two 3mm tall test prints.
2. If desired/needed, ream the holes. I did.
3. Dismantle the bot, add those bad-joke-looking-like-cheap-made-in-ch...(sorry) bushings to the assembly and assemble the bot again.
4. Oil/grease (I use lithium grease)
5. Don't ask your money back to me if it finally doesn't works :-P