Introduction: Prothestic Hand

Picture of Prothestic Hand

This prosthesis has been designed to help those people with missing fingers.

It has been modelled keeping in mind the following principles:

  • Keep the number of printed parts as low as possible. -Keep the assembly process as simple as possible.
  • Use the least possible amount of non-printable parts. In this new model, you can choose how to join fingers, using screws (2M), axes wire, or filament printer. Leave openings in the model to allow the hand to transpire.
  • The previous model had another hand rotation system on the wrist, had more freedom. On this occasion I have modified the movement of the wrist using the fantastic idea of a union that uses hand "Flexy-hand v2"
  • I have also modified the system of tensioning the strings. It is safer than before and takes up less space.
  • I have included a version without thumb for those who have their own finger.

The fingers flex when they are pulled by strings, such as fishing line, and extend automatically with the help of elastic cord. A fabric strap with velcro is needed to secure the prosthesis to the arm.

You can download the original file blender, and thus can be studied and modified to improve its performance.

I hope to be successful with modifications. Thank you very much to " Africa Directo" for suggesting changes and help to improve the model. Isaac texting Prothestic Hand

This design is based on my previous design.

You can download and view files here:

Step 1: Materials

Picture of Materials
  1. Printed pieces
  2. Pliers
  3. Soldering iron
  4. Emery
  5. Choose the connection system parts between:
    • Filament printer (1.75mm)
    • Screws and nuts M2 10x20mm and 10x10mm. And superglue to fix the nuts.
    • Wire and filament printer
  6. Fishing line
  7. Elastic cord 1mm diameter
  8. Velcro strip

Step 2: Joins Parts: Wrist and Hand

Picture of Joins Parts: Wrist and Hand

La pieza de conexión debe ser flexible. Para imprimir esta pieza utilicé filamento flexible "filaflex".

The connecting piece must be flexible. To print this piece I used flexible filament "filaflex"I have also used flexible filament thus provides better grip for objects, although in this case is optional.

Step 3: Jointing Together the Pieces of the Fingers.

Picture of Jointing Together the Pieces of the Fingers.

Choose how you want to join fingers. I'll show you three options:

  • With screws and nuts M2 10x20mm and 10x10mm. And superglue to fix the nuts.
  • With Wire and filament printer
  • or Only with filamentof printer (1.75mm)

The easiest option is with nuts and bolts, but if you do not have to hand can use the other two ways union. As you will see in the video finally to join the fingers, I chose the option filament wire.

This is the order to assemble the fingers:

  1. Insert the elastic cord in "distal" piece.
  2. Join "link" piece.
  3. Enter the link piece and the elastic cord in the "proximal" piece.
  4. Make sure that the elastic cord is on the outside.

  5. The middle finger is the first finger should be placed, then put the ring finger. The order of the fingers is not important in the assembly.

Step 4: Places the Cords in Hand

Picture of Places the Cords in Hand

In this video image and you can see how easy it is to place the cable. Depending on the fishing line you use, you may need help with a wire insert.

The elastic rope is tied in the palm of the hand. The non-elastic cord is attached to the wrist using pieces "tension". Only you need to tighten the strings to your taste and place the cover to let them fixed.

Step 5: Velcro

Picture of Velcro

Uses Velcro to attach the hand to the wrist. Velcro with adesivo is very comfortable for it.

Velcro 40 mm wide will be perfect. Also, you can find it in different colors.

The hand is finished


ozter (author)2017-01-25


A question: are you able to create an sti for a
below the knee prosthetic that can be printed on a Prusa i3 [stereo
lithographic printer]?

The reason I ask is that I have a
friend who has been waiting for 4 years for his leg from the government
hospital, and would like to help him out; I also have a friend who owns
the machine.

I have spent many hours on the `net, scouring for a leg sti, but to no avail.

Hence my contact to you.

Thank you for your time

HiramG3 (author)2016-10-06

Is the size based on an adult? Is it possible to scale down for a 9 year old? My son has a left hand deformity and I am interested is paying to get it printed.

SoniaVerdu (author)HiramG32016-10-15

I think you can reduce a little, may only 1/3 because if further reduces the space to pass the ropes can be closed

Meglymoo87 (author)2016-04-29

Nice! I would LOVE a 3D printer...there's just SO MUCH you can do with it!

AllenInventions (author)2016-04-26

I already made that same one but I had problems with the tensioners wearing out


What kind of problems you have with the tensioners?

The holes wore out. Might've been better out of abs? The elastic string also doesn't make it spring back quite enough. Overall though it did work and looks super cool great design.

Lineakat (author)2016-04-27


IshaqA1 (author)2016-04-27

just Great

kart15 (author)2016-04-26


watchmeflyy (author)2016-04-25

Your hand looks more realistically curved than other models that I've seen; great job!

DylanD581 (author)watchmeflyy2016-04-26

I agree; it's one of the best models of its kind.

studleylee (author)2016-04-26

So well designed! Very cool looking!

That Redhead (author)2016-04-25

This is amazing.

About This Instructable




Bio: I was born in Madrid, Spain. I started drawing and modeling in my early childhood. I studied Fine Arts for five years at the University ... More »
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