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Mold making question

Discussion in 'Special Effects' started by egorleski, Sep 6, 2006.

  1. egorleski

    egorleski Member

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    I want to make a giant remote control rat. that being said i need to procure a giant rat that will read as such on stage. I want to custom make the rat so that i can get it the size i want and to mount everything i need inside. We dont have the equiptment to scan a small fake rat and then enlarge it and use the computer to make a new mold. I was wondering if anyone knew of any way to take a small-medium plastic rat and make a mold for a large rat. thanks
     
  2. Footer

    Footer Senior Team Senior Team Premium Member

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    Might want to bust out your art skills on this one, and if you don't have any get some one who does. The easiest thing to do would be to make the initial "creature" out of foam. Make a foam cube and sketch what the top, front, and side projection will be. Carve down from their. How big do you want this thing to be? I assume you are going to mount an small RC car in it?
     
  3. cutlunch

    cutlunch Active Member

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    For the big rat you can use fine wire netting to shape the body then paper mache or fibreglass the body on. Paper mache cheaper of course.
     
  4. SHARYNF

    SHARYNF Well-Known Member

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  5. egorleski

    egorleski Member

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    Yea the lazer scanner is definantly out of our budget but amazing technology. We are going to mount the rat on a small rc car and put in some LEDs for the eyes. We want it to be in plastic or at least parts in plastic, like the tail and legs, so that it will look more realistic. Yea, theres always the tried and true method of sculpting i was just curious if theres a way to do something like the lazer technology does by taking a already existent plastic rat and enlarging it without spending a million dollars.
     
  6. Footer

    Footer Senior Team Senior Team Premium Member

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    You could always do some type of fiberglass over the foam.
     
  7. SHARYNF

    SHARYNF Well-Known Member

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    There is a manual method similar to how it is done to make large sculptures from modles. You have to take your small model, and then mark it with a grid, then you take those measurements and multiply them by your scaling factor. It takes time but you use a set of calipers.

    the other thing that people have tried is to make a mold of the model from a material link a baloon, and then inflate it carefully, in theory the equal increas in pressure inside would more or less increase the size uniformly.

    Most of the time it is really a combination of having the modely, haveing the grid markings on it, and then molding your own using the model and the calipers for reference but still taking a lot of practice and time


    There is a third option and since you in Chicago you might be able tofind someone with the machine, you want to find someone with a rapid protyping maching. I don't know if you have ever seen there, basically over symplifying things it is like a lnk jet printer that operates over a liquid that when activated at a specific point, hardens, the machine basically builds up your model layer by layer, hardeing the liquid until you have the model. They are used to make quick molds for one off parts, YOU MIGHT Be able to convince these guys in your area who could donate running one off for you. They are totally awesome to watch it is like this monster coming out of the deep soup and being born

    http://www.pardev.com/sculpture.html
    they are called Paradigm Development Group
    1435 Elmhurst Rd.
    Elk Grove Village, IL 60007


    Sharyn
     
    Last edited: Sep 7, 2006
  8. saxman0317

    saxman0317 Active Member

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    Easiest thing to do here is just make a gelled mold. Just make a free form clay model, or foam even. Do it by eye...besides, its a rat, get the general point across as to shape, stick some hair on it, and people 20 feet away are happy. rats are ugly anyways. After making your model, cover it in a release agent (i just use crisco) and mold around it with a gel mold material, from any local art shop. From there, see if you can find some type of fleshy material would be best, coat the inside of your mold in more lreaase agent, and then do several layers of this fleshy stuff in side to make yourselfa hollow rat. Take your RC guts, stuff it inside on a crude frame, stick some hair in with a needle, maybe do soem smoke from the nose, some glowing red eyes, snot dripping nose, and your set. Maybe get some servos and make the mouth and neck move? Legs move?
     

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