How to build up a solid surface on plastic?

entilza · Post by **entilza** » Wed Jul 11, 2012 10:14 pm

Hi team,

First time scratch builder, looking for advice:

I'm building a prop for a short film. It's a futuristic stun gun. I've bought a plastic toy that I've altered to my needs and have already done a test paint on. The view you see below is showing the "business end" of the stun gun, where the electrodes will be attached to:

http://www.redsector.net/eg/gun.jpg

The two brass (copper-looking) electrodes look like this, and are flat on the end that will be attached to the gun. The right one shows the flat bottom:

http://www.redsector.net/eg/brass.jpg

Attaching the brass to the plastic would normally be easy: super glue. But I want to build the gun surface up, so they are angled in towards each other at almost a 45 degree angle, as per this pic where I am holding an electrode on the gun:

http://www.redsector.net/eg/gun+brass.jpg

I'm trying to figure out not only what is the best way to build up the "missing" part that will allow me to angle the brass, but also have it be solid enough that it can be handled by an actor, held to someone's neck, etc.

Also: any advice on how to smooth out that yellow paint? It's brushed by hand. Perhaps I should have spray painted it?

All advice appreciated! Thanks!
Ent.

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chiver · Post by **chiver** » Wed Jul 11, 2012 10:38 pm

first, you might not notice the yellow on camera, it might looks cleaner once its on film. secondly, theres two ways to do it, cut into the gun. make a trench on the angle you want, or plastic rod.

Stu Pidasso · Post by **Stu Pidasso** » Wed Jul 11, 2012 10:41 pm

Go to your local auto parts supply store and pick up something called "JB Weld." It's a 2 part compound, that when kneaded together, then cured, forms an indestructable steel-like bond. You have a few minutes working time to form and manipulate your shapes, but once it's hardened, that's it, it's on for good unless you have a grinder. Good luck!

Or, you could go Aves, and use super glue to attach it that way.

entilza · Post by **entilza** » Thu Jul 12, 2012 12:26 am

Firstly: oops, sorry about the inline images. My bad, I should have read the rules closely. Not a great start.

Thanks for the suggestions so far.

chiver: A plastic rod! Great idea - could be cut to be real short, just giving the angle really. Just need to figure where to source such a thing.

Stu: Is JB Weld seem to offer various versions - metal, wood, general. The version you've linked appears to be metal? I'm wondering if I can make a mold and "kneed" it into the correct shape, just before placing it. Problem there may be how small the mold is and how angled it is - will probably cause issues.

Thanks everyone!

Mr. Badwrench · Post by **Mr. Badwrench** » Thu Jul 12, 2012 4:45 am

Do you have hobby shops or model train shops in your area? If so, they will probably carry plastic stock in sheet, rod, and other shapes. Hopefully you can find some stock that will suit your needs, or something that can be easily cut and sanded to shape. Regular hobby shops are a good place to look, but I also suggest model train shops because they are often overlooked by regular modelers, and yet they usually have a larger selection of scratchbuilding supplies.

Rocketeer · Post by **Rocketeer** » Thu Jul 12, 2012 10:05 am

JB Weld is not really workable; it's sticky and viscous, so won't hold a shape and sticks to your fingers, to boot. If you choose to use a putty you'd do better to get two-part plumber's epoxy ribbon, or, if you have a good hobbyshop nearby, Milliput (I suggest Milliput White) or Aves Apoxie Sculp.

Plastic rod you could get online from Plastruct; I think Evergreen also offers online sales.

For your purposes, since props can be a bit rough, wood dowel might work as well, with five-minute epoxy as an adhesive. Both would be available at a hardware store.

karim · Post by **karim** » Thu Jul 12, 2012 12:17 pm

As a prop, it's got to stand up to a little more wear and tear than a typical model. Aves Epoxy putty all the way. You can order it right here from SSM.

Tankmodeler · Post by **Tankmodeler** » Thu Jul 12, 2012 4:24 pm

karim wrote:As a prop, it's got to stand up to a little more wear and tear than a typical model. Aves Epoxy putty all the way. You can order it right here from SSM.

True, but if time is of the essence and he doesn't want to wait for it to be shipped to Oz, then a wood dowel cut to suit, epoxied in place and then paintedwithj a dark colour to hid the grain would be fine. If there will be an extreme close-up (there the grain might be seen) paint the dowl before installing it with a filling automotive primer and tehn sand back to a smooth surface.

You can also use thick wire, thick solder, get a friend with a lathe to turn down a small piece of aluminum or brass, etc, etc, etc, etc.

Lots and lots of ways to skin this cat.

And yes, if you want to not see the brush strokes, spraying would be better in all circumstances.

HTH

Paul

skymods · Post by **skymods** » Thu Jul 12, 2012 4:24 pm

I'd make the wedge out of balsa wood. Super simple to cut and shape. Give it a few coats of super-glue to harden up the surface. Then paint to match.

Dave

entilza · Post by **entilza** » Sat Jul 14, 2012 4:56 pm

Hi all,

Thanks for the continued advice.

The Salsa wood & super glue idea sounds interesting. It will allow me to easily get a naturally angular shape. I've never coated something with super glue before - that would be interesting! Obviously I'll need to attach it to a screw and put in a vice for handling.

Plastic rod or dowel may also be options - I'm thinking of changing it from an angular wedge to a similar circular shape that is angled, so the brass just comes out of this shape.

Let's see how I go this weekend! Thanks everyone. Great ideas.

Ent.

entilza · Post by **entilza** » Sun Jul 15, 2012 2:53 am

Hi all,

I ended up solving this problem by instead of extending the surface of the "gun" in a wedge, I instead extended the length of the brass "electrodes". I found a piece of brass pipe in the hobby store that was the perfect OD. Hacksawed them to the right angle, super glue, and away we go.
http://www.redsector.net/eg/gundone.jpg

Thanks again for everyone's input. As always the simplest approaches are often the best, but I've come away with some great info and ideas for future problems. :-D

Ent.

Mr. Badwrench · Post by **Mr. Badwrench** » Mon Jul 16, 2012 4:56 am

That looks fine man. Brass tube was a perfect solution.