The UnLimbited Arm 1.7 - Isabella Edition.


This release contains all the required files to create the The UnLimbited Arm. The arm us currently at Version 1.7 and named the Isabella Edition in recognition to Isabella, the worlds 1st recipient of the arm who kindly agreed to work with us in its development.

Isabella previsouly received a RIT arm from Team UnLimbited, we wanted to create a new device that would be easy to print, lightweight and functional. We hope this device will be of benefit for the e-NABLE community, and many recipients both in the UK and globally that could make use of such an assistive device.

We hope that the e-NABLE community will evaluate, build, provide feedback and evolve this device design to help improve it as we all try to give the world a helping hand; or helping arm in this case !

Key Usage Statistics

  • The UnLimbited Arm is currently compatible with the e-NABLE Phoenix hand and is suitable for use with recipients that Phoenix hand scaling is within the 100 - 130% range.
  • Arm sections scale inline with the Phoenix hand.
  • Suggested print settings are as followed :-
    • 3 Perimeters / Shells
    • 35% infill, suggested honeycomb if available.
    • 4 Solid Top and Bottom Layers
    • Tricep Cuff will currently require support to print correctly; we use Simplify 3D built in support feature to do this.
    • Tricep Cuff forming Jig that scales at same size as the cuff for easy forming and uniform shaping.
  • The device is printed in PLA and then thermo-formed into its final shape, NOT suitable for printing in ABS.
  • As the recipient will have no palm, we use a thermo-palm version of the Phoenix palm which you can find HERE.

Future Roadmap and Development

The following items have already been identified as enhancements to the current design that need to be developed. Team UnLimbited welcome anyone to evolve the design in relation to the items listed below !

  • Modification of Tricep cuff and forming Jig to allow for the cuff to be printed totally flat and then formed into the correct shape. This should aid with strength, reduce print time and remove the need for support material.
  • Creation of a top cover or residual forearm plate to help with fitting for recipients with a short residual forearm.
  • Creation of scripted parametric workflow in Autodesk Fusion 360 to allow for correct ratio scaling for recipients above 130% This would also allow for arm part generation to be presented as "Arm-O-Matic" in the future.
  • Modification to forearm into sections to allow for larger arms to be printed on smaller / standard print beds. (This was a feature we have developed and tested that has currently been removed due to recipient arm ratio complications above 130%)
  • Adaptation of the Forearm to allow for fitment of different hands such as the Raptor Reloaded.
  • Many Many more ideas ...

Release Contents

This release contains the following items :-

  • STL files ready to print for all arm components, these components scale inline with the Phoenix hand.
  • STL file of modified Phoenix Palm with integrated Thermo Palm.
  • Link to the UnLimbited Arm sizing spreadsheet guide to assist in correct arm sizing and dimensions.
  • Autodesk Fusion 360 archive of all arm components to allow for future modification by the e-NABLE community.

Please note that all STL files are for a Left hand / arm. If building a Right arm, the palm and the forearm will need to be mirrored; the cuff is ambidextrous.

Build Instructions

Correct sizing of the UnLimbited arm is calculated by comparison of 4 separate measurements, to simplify this process we have developed a sizing spreadsheet to help determine best size; we are still refining this method but to date it has proved to be accurate (within the 100% to 130% size range) Without going into to much technical detail (and 3D Build plate size limitations) it is advised NOT to attempt arms that work out at over 130% even if your build volume allows you to do so.

3 of the measurements are taken from the recipients non-affected arm as shown in the diagram below; the 4th measurement is the diameter of the tricep for the cuff fitting.

Suggested method for taking measurements is the standard e-NABLE method using Tracker.

For the tricep size to fit the cuff one suggested method is to use a piece of string or dress makers tape measure to first measure the circumference and then convert it to a diameter. You may also want to take measurements at the top, middle and bottom of the tricep to determine an average as they can be variation due to muscle mass; Team UnLimbited are still working on the best method however we believe using multiple simple methods and comparing the results provides the best chance of good results.

We strongly advise that all measurements are shared back with the recipient or their parent / guardian so they can be double checked.

Example Sizing Guide Usage

Below we can see an example of the sizing guide in use. All recipients measurements have been entered, in the example below the Sizing confidence indicates the arm and Phoenix hand should be scaled and printed at 100%. 

Things to look out for when determining size :-

  • The non-affected hand and Phoenix hand should not have to much size variation between them, but typically the Phoenix hand can be slightly larger.
  • The length of the non-affected arm the completed UnLimbited arm with Phoenix hand should be pretty much the same length when fitted if the scaling is correct.

Once you have determined the correct size you are ready to print all the arm components and Phoenix hand.


Required Materials

Other than good quality PLA for the actual arm and hand elements we recommend the following other items for your UnLimbited arm.

  • 1mm or less uncoated dyneema fishing line for the tendons.
  • Dr Scholl Moleskin Plus Padding for lining the cuff and inside the forearm.
  • 20mm wide double sided velcro or velcro straps for the cuff and Forearm.

Arm Construction

Please see the video below that shows some footage of the UnLimbited action and some guidance on how to assemble the arm.


File Downloads and Links

  • The STL Files for the UnLimbited Arm are HERE.
  • The STL File for the Phoenix Thermo Palm Hand is HERE.
  • The Sizing Spreadsheet can be found HERE.
  • The Autodesk Fusions 360 archive can be found HERE.

Licensing and Usage

Creative Commons License

Team UnLimited The UnLimbited Arm by Team UnLimited is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Based on a work by Po Paraguay, Christian Silva and the e-NABLE Community.
Permissions beyond the scope of this license may be available at