Do you have an Omnibot 2000 robot - http://www.robotsandcomputers.com/robots/personal... - whose arm is just hanging limp at his side? More than likely, the problem is a broken arm joint. You can see where this common-failure part breaks in the second and third photos. I glued mine back together long enough to make a silicone mold from which I then cast a functional, albeit ugly, replacement years ago. Now that I have a 3D printer... why not use it for something useful?

Step 1: Roll Your Patient Into Surgery

First things first, you will need to operate. Be sure to wear a surgical mask to hide your identity... I mean, to protect the patient from infection. Extract the damaged joint and set it aside, being sure to label everything as you go to aide in reassembly. Once that is completed, hook your bot up to an IV drip while we print a new arm joint - it'll take two to three hours. We wouldn't want the patient to dehydrate while on the operating table, now would we?

Step 2: Print a New Joint

You can download my reproduction part from my Thingiverse profile here - http://www.thingiverse.com/thing:2189603

In the photos, I should point out that the grey piece is the original while the purple piece is the replacement.

Once you have the STL file, print it using any resolution you like. 0.1mmm will result in a better looking part, but it will take much longer to print. 0.3mm is generally sufficient for a part that is heard but not seen, so to speak.

You should set the wall thickness should be set to 0.5mm with 2 walls to account for the top threads. If you can print the model with standard wall thickness and line count up to the flat portion with a reduced thickness beginning there, it'll produce a prettier print.

Finally, if you slice the model with Cura, the support material breaks away VERY easily with XY-Distance set to 1mm.