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Easiest/cheapest way for a beginner to cast custom plastic parts? Answered

I tried searching, but I couldn't find anything that fit exactly what I want to do.

I have a hard plastic figure and I'd like to be able to create removable pieces, such as armor, for it.

I'm thinking that what I need to do is to sculpt what I want to make directly over the figure using some type of modeling material, make a mold of that and then cast it in the final material? I'd like the finished pieces to be strong and durable, and not fragile/brittle.

I even thought of sculpting the pieces directly out of epoxy putty since people say it's strong and rock hard when cured, but I've never used it before and I wouldn't know how to keep the pieces from adhering to the figure, but still let them stick until they've begun to set and then be removed without deforming them. I don't want to damage the figure or end up with bits of material permanently stuck to it.

Please keep in mind that I have NEVER made a mold or cast anything before. I have no fancy equipment and I live in a relatively small town with virtually none of the specialty stores that every other DIYer in the US seems to live five minutes away from. I see Halloween projects where they say you'll need a quart of liquid latex and that you can get it at any theater supply shop for about $10. Um no. More like five ounces for $10 at a craft store. If I can't get it at a mainstream chain store, I'd probably have to order it online and I would really like to avoid spending $50+ for something that's just a fun project.

What would be the easiest and cheapest way to do this?


I tried to edit this, but it doesn't seem to be saving the changes. I meant to say "strong and durable" rather than "hard and durable".

I am going to sound like a jerk, and I am kind of intentionally.

Do you just want someone to do it for you? You seem to not be able to do anything and turn down every suggestion. If you have no skill to do anything whatsoever, why try? Why waste time asking others how?

Here is an idea... TRY... use the suran wrap and put that over some soft worked water based clay. Let it harden up from natural drying. Then take a pointed object and etch away until you have something close to what you want. As soon as you have your item, then you can go to hobby lobby and buy a casting kit for $25.00 us.

Make a rubber mould for/of your clay part, then after your mold is made, pour your epoxy or acrylic into the mold. Poof, your done, then its just paint.

Simple, easy and complete. all for less than $30.00

EVERYTHING is all on you. if you cant make your part, then don't bother asking. I am not going to etch/make your pieces. I WILL help you cast it once you have a sample.

Use WWW.GOOGLE.COM and just google some of the suggestions offered to you above. No more excuses, just go do.

put the wrap over the clay. Then press your base item into it. Then let the clay dry. then pull your part out, pull off the plastic, now cut down and etch your part you want. I accidently deleted this section just before publishing.

One can cast hot glue.
Not the detail expected of pro casting, but injection molding is done at teens of 1000s of psi.

"One can cast hot glue."

I'm looking to do this as easily and as cheaply as possible. For all I know, I'll be completely inept at sculpting anything, which would make the whole question of making molds and casting parts moot. I mean, what's the point of buying all those supplies and going to through the trouble of trying to make molds if I can't even sculpt what I want properly?

Call me lazy, but I'm more interested in the finished product than in the process to make it. If I could have someone 3D print what I wanted for a cheap price, I'd do that instead of trying to do it myself.

hot glue is about as cheap as anything you can buy. but you can dig clay out of the ground almost anywhere on earth.


4 months ago

The new owner of this site appears to be trying to turn it to a mobile phone site with inadequate cod monkeys (a sad mistake)

Use saran kitchen wrap to prevent sticking and wax or thixotropic epoxy...

Amazon sells no sag epoxy but I prefer the "Lost Wax" system (much more detail) depending on your skill level..

"Use saran kitchen wrap to prevent sticking and wax or thixotropic epoxy..."

I don't think that would work too well as there are various small details that would prevent the wrap from conforming to the surface.

"Amazon sells no sag epoxy but I prefer the "Lost Wax" system (much more detail) depending on your skill level.."

I have no idea of my skill level because I've never actually done anything like this before. I've watched videos of people using epoxy putty and it looks easy enough to shape. I'd want it to conform to all the details, but not stick permanently. Ideally I'd like to be able to coat the figure with something, place the epoxy putty directly onto it, sculpt it into the shape I want, leave it until it begins to harden, then pop it off without distorting it and allow it to fully harden. I don't know if that's even possible though.

the Saran wrap is only to easy remove the epoxy putty..

Why are you concerned about the inside details which no one will see ?

You are supposed to look up lost wax yourself !

There are fluid dips for nonstick removal after dry but you wanted to keep the cost low !

. Uee plaster of paris to make an open mold - Vaseline or any grease will stop things sticking.

You can then press your chosen material into the mold, Personally I might think of using Sculpty (Fimo in UK) - it sets semi flexible.

"Vacuum forming isn't all that hard and you can recycle milk jug containers for it."

Same problem; I don't have an item to create a mold from. I have an image in my head and that's all. Building a vacuum forming machine isn't going to help me if I have nothing to make in it. Also, Every vacuum formed item I've ever seen has been thin and weak, which is pretty much the exact opposite of what I want. I want relatively thick, strong finished parts.

"Uee plaster of paris to make an open mold - Vaseline or any grease will stop things sticking."

I don't want to duplicate an existing item, I want to create a NEW part that fits on an existing item, but that is not permanently attached. The new part(s) that I want to create don't exist anywhere other than in my mind at the moment.

Have you ever seen those Halo action figures with all the removable armor that snaps into place on the figure? I want to make the equivalent of that armor; Fits on the figure, but is removable.

It needs to be sculpted on the figure to ensure a perfect fit, but without permanently sticking to it. The finished items should be strong enough to be attached and removed without being brittle.

If you've never molded or cast anything before a good place to start would be the Mold Making and Casting Class here on Instructables.

I've never made a mold or cast anything before either, but I've enrolled in the class and I'm hoping to turn out my first cast next weekend.