Project of mechanical hand/arm prop.

Charles Emeriau-farges

Hello there, 

(My second post on the forums, yeepee !) *cough*

I'm currently working as a multi-task-technician-artist on a post-apocalyptic webseries, and, within my domain of work, is also the costume/props design part of all.

And so, as the project advances, we have to make more and more props, more and more techy things to go with the series, and, well, it's getting harder and harder : it's easy to make a good-looking gun, it's waaaay less making a nice armor (though, i'm getting used to armors, not not such a big deal nowadays).

But, this time, I think i'd require some advices, and well, this forum seems to be the perfect place to get a helpful hand on prop making, right?

Soooo, here's the thing. Among all the characters of the series, three of them are supposed to be augmented humans, via some modifications either biologically speaking and by some prosthetics when needed. (litterally, they're kinda like spartans with less  bio-tech modif's.) (I might explain more if needed/wanted  ).

And, among those guys, one of them has lost an arm and a leg (hoho what a neat joke, he?) and, therefore, he has gained some shiny-bright bionic limbs. Including a mechanical arm and hand. (actually, the mecha part goes from the elbow to the fingers).

I've done a little sketch of what I've got in mind.

And, well, I'm asking myself how to make it, since i know how to make armor parts, but this arm should not be too big, as it's supposed to replace the actual limb of the guy.

So, i was thinking about thermoformed EVA foam or maybe plastic sheet (worbla-like) for the main parts (the plates) but, I need them to be a bit moving (more or less like a lizard'scales, if you see what I mean) and THAT PART, i don't know how to make it.

So, this topic will be open for me to post the work in progress of the said prop, and if anyone has ideas on how to make the parts moving yet tied together, i'll be more than happy if you share these ideas with me  

Well, that's all at the moment, thank you all in advance !

~Charles/

Chris Ellerby

I'd start with a life cast of the actor's arm, then cast up a plaster version of his/her arm you can sculpt or fabricate on.  One simple option is to vacuum form some ABS over the plaster arm then start cutting up/layering the plastic to create a form fitting shell.

The challenge is that it's a prosthetic arm (replacement) rather than armor (addition) so it needs to be thin and form fitting to avoid looking like bulky armor.

Worbla is a good material for projects like this, as is vacuum forming with ABS or other sheet plastics.

As for having moving parts that are tied together, one great trick is to have components that look like pneumatic/hydraulic cylinders that move as the performer moves the arm/fingers.  They are easy to fabricate using a rod/tube that can slide in and out of a larger cylinder.   One popular example of this C3PO from Star Wars.  He has some actuators on his arms with a bit of movement.

/Chris