Instructables
Picture of How to make molds

This Instructable is an introduction to the basics of mold making for people interested in mold making with little to no knowledge on the subject.

It will walk you through some important vocabulary, break down the major mold types and help you select the correct mold for your project.

Here are some great mold making resources:

http://www.smooth-on.com/

Tap Plastics

http://www.aeromarineproducts.com/silicone-mold-making

 
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Step 1: Types of molds

There are a variety of mold types for different applications:

  • Pour mold - Mold made by pour silicone over an original inside of a containing box
  • 1-part pour mold (block mold) - a pour mold with only one side (simplest type of mold)
  • 2-part pour mold - a pour mold with two or more halves and registration keys to align the parts
  • Brush-on mold - a mold made by brushing on thin layers of silicone to build up a skin that is then encased in a rigid mother mold to give structure while casting
  • Glove mold - A brush-on mold that does not require a parting line (sometimes uses a small slit)
  • 2-part brush-on mold - A brush-on mold that is split into two or more parts
  • Lifecasting - Mold made of a living human

Diagrams of the cross section of several mold types

Here is more information on Mold types.

pgamurot1 month ago
May I have your mail so I could ask you things about molding?
rlciavar (author)  pgamurot1 month ago

Post any questions about molding here incase someone else has the same question!

The part I want to reproduce is a hard nylon think I can make the mold. What material could I use to have a hardness like Black Nylon

Smooth-On's Onyx resin is a good choice. (And it's black too!)

Afaik, nylon is melted, not two part cast.

rlciavar (author)  KayakFishnFever4 months ago

There are lots of options when it comes to selecting a material to cast in. I haven't come across any nylon casting materials (though I'm sure they exist). Smoothon.com has a lot of different options, plastics, foams, rubbers, etc. I usually use Smoothcast 300. It is a very strong plastic, however it's a bit brittle so I wouldn't use it for anything that will take impact. Maybe start by looking at the different polyurethane plastics at smoothon. Let me know if you find an interesting material!

danzo3214 months ago

In fact, a lifecast mold is not really a separate category; they can be simple, complex, poured, painted-on, etc. Big difference is there's a person in there!

Taytora4 months ago

New to molding/casting and was wondering if I could get your input. I want to replicate a picture frame I have. What type of mold would you suggest? Thanks!

P1040716.JPGP1040717.JPG
rlciavar (author)  Taytora4 months ago

Since there are only features on one side, and the other is flat I would use a one part pour mold as described in the instructable

Donio4 months ago

Everything I saw was links to other instructables. Do you not show and tell how to make molds? I could have searched other instructables without reading this.

rlciavar (author)  Donio4 months ago

This instructable is a broad overview and introduction to the world of mold making. It teaches you the basic vocabulary and reasoning behind choosing a mold. It would be difficult to fit all the types of molds into one Instructable so instead I included links to each kind of mold. If you're interested in how to make a specific type of mold reference the links provided for each kind.

Thanks for the Instructable. I've been planning on doing a mold and cast of my friend Yorik. It looks like a two part brush on mold would be the best for him.

yorik01.jpg
fixfireleo4 months ago

haha...from the thumbnail on the instructible email, i thought that was a urinal. i was thinking, "oh wow, how handy!!" :) (they cut off the top of the helmet)

here is the part photo

gear.jpeg
wow! that's some detail. you've made it exciting enough for newbies to try their hand at some molding. thanks for this.
rlciavar (author)  hardlydavidson4 months ago

No problem! give it a try it's a lot of fun!

poofrabbit4 months ago

Fantastic instructable thanks so much for posting!