Many of the filament guides I've seen require either more vitamins (bolts/nuts/rods), or the removal of the frame nuts for installation. I had a heck of a time squaring and tightening my frame, so I didn't want to have to take it apart again.

This filament guide is a snap-in one designed for the pitch of the threaded rods on the original Mendel (58.89mm). I don't know if the Prusa has a different pitch, but this guide should work even if it is up to about 5-7mm narrower than the Mendel (obviously wider won't work so well without modification).

I printed one out of PLA and it snaps in nice and snug. ABS may have different stiffness.

I also used the diagonal slot idea from fil's thing thingiverse.com/thing:11222, but I moved it around to the top like he suggested so that the guide can be installed "either way".

This is a mash-up of the spindle from "Heavy duty filament spool - for mendel by watsdesign" (http://www.thingiverse.com/thing:11447) and "Snap-In Mendel Filament Guide, with diagonal slot by toomanyplugs" (http://www.thingiverse.com/thing:11521)

I needed a filament guide after printing the heavy duty spool, I seemed to me that I would be even better if the parts were combined.

Since both source files were in different formats I combined the stl's in openSCAD. The edges may be a little rough where I had to clean off the protruding edges.

This is a 100% printable filament spool based heavily upon randyy's design.

Changes:

Added webbing to arms for strength.
Modified dovetails for better fit (the original required a lot of sanding to get to fit well - for me).
Increased arm thickness for strength.
Increased mount size for strength and more solid connection to MakerBot.
Changed geometry of birdmouth slightly.
Increased size of filament holder so that more filament could be wound on spool.
Added hole in the filament holder.
Beefed up the filament clip on the filament holder.
Enlarged the conical pieces that press fit into the arm for more secure fit.
Added a filament guide for use with Cupcakes.

inspired by thingiverse.com/thing:12153 (mount bit)

added shoulders so head of screws would not ride on back of spool.

This was done by my 10yr old, who knows sketchup better than I do, in about 5minutes

Recognizing that it will take a while longer to get the full working printable gearbox, I'm releasing parts of it in incremental updates.

The DC motor clip should be pretty handy-- the motor it's for is common and cheap, so this geometry should make a decent starting place for simple (non-geared) robot applications and other things.

Articulated modules for building modular robots. It is the repraped version of the Y1 modules that I have created for my PhD.
iearobotics.com/personal/juan/doctorado/Modulos-Y1/modulos-y1.html
Version 1.0 is the first one. It works and it is 3D printable, but the design should be improved in order to obtain a better printing quality.

UPDATE: 09/Nov/2011
A new version has been released: thingiverse.com/thing:13442

Its a design for a small office catapult. Now you can bombard your boss with small stuff. Best results with 3M notes.

Feel free to adapt it as stated in the licence.

A small desk clamp.

Works but it requires a little more super glue than I would have liked.

It was designed to be a PCB holder (the one Lady Ada uses in her instructions was the inspiration).

ladyada.net/images/usbtinyisp/tools.jpg

The base is too small making it unstable.

However I just finished printing it and it works!

To make it you will also need.

3/8 (5mm will do as well) threaded rod and some square nuts.
Square brass tubing ( 3.9 mm ) and the size that fits just inside that.

Needs some more work:

Bigger base , maybe multipart
Better way to hold the clamps

The tar file contains the blend , photos and all the stl files.

This 43" tall, 46" square dining table assembles with no hardware or glue. It is incredibly sturdy.

The table is square because it promotes better community with no one placed at the head of the table and everyone equidistant, allowing for better conversation.

The table takes 2 4"X8" sheets of 18mm plywood. Most cabinet grade plywood from Home Depot is 18mm and inexpensive. The one in my home is made from high grade birch ply.

Please check out jeffreymatthias.com to see some of my other work.

Someday, I will alter the design to allow for an expanding top to accommodate 8 people.

I've added a photo of it in our home for an idea of how big it is.