Here's a handy little cardboard spool you can use for your MakerBot filament. I designed it for a thicker cardboard than pictured, but all I had around when I was inspired were some pizza boxes.

As posted on my blog http://charlespax.wordpress.com/2010/01/08/cardboard-spool/

See it in action as part of the future Bowden filament drive box http://charlespax.com/2010/01/26/makerbot-filament-box-and-drive-mechanism/

The latest version can be found in subversion at http://svn.makerbot.com/users/charles/bowden/ .

EDIT 2010-03-21: I added a divider to the files. Thanks, Kevin. I also decreased the size of the hole that secures the filament to better grab the it.

Cut out two flanges and one barrel. Bend the barrel so it curls and feed it into one of the flanges. Fold the tabs back into the flange through the smaller holes. Packing tape helps to hold them in place.

Now you'll have a top hat crown thing. Place your filament roll over the barrel and put on the other flange. Again, tape helps.

A 10 mm shaft through the arbor hole and you're ready to print. Well, you'll probably want some sort of mount for this. It's coming...