Learning the ins and outs of molding and casting may not seem like a great benefit to the average maker. It may also seem like a strange kind of unapproachable alchemy, with all of the noxious chemicals, mixed in specially marked cups, at exacting quantities. And then there’s the apparent difficulty in proper mold making, casting inside vacuum chambers, and other molding and casting exotica.

The truth is that being able to create a mold and cast a part, for everything from a machine repair to Halloween costume creations, can be a huge benefit. Once you know the basic ins and outs of molding and casting, you’ll be looking around the house for objects you might want to duplicate.

Here is a collection of helpful molding and casting tips that should be of benefit to every caster, from the hobbyist to the professional.

Working with Epoxies 101

Maker extraordinaire Andy Birkey was asked by one of his YouTube viewers for any tips on working with epoxies, casting resins, and the like. Here was his response:

Normally, I’m a do-it-as-you-go, seat-of-the-pants kind of guy. But when it comes to epoxy, it’s chemistry; it’s math. You have to do it exactly right. That’s one time I don’t futz with things. I just do what they tell me.

Buy the best I use the best epoxies I can afford.

Measure accurately I use a digital scale and try to get everything as close as I can.

Temperature Make sure your temperatures are right. That’s very critical to proper curing.

Know your material Get to know your material, and experiment as much as possible. Try it on little things that you don’t care about. Get comfortable with the chemicals.

Getting Bubbles out of Epoxy

To get the bubbles out of epoxy (if you don’t have a vacuum chamber), use a heat gun or hair dryer.

Dissolve ShapeLock in Chloroform

ShapeLock plastic is a great molding and building material for lots of projects. ShapeLock, also known as polycaprolactone, becomes moldable at around 160&degree; F and hardens to a nylon-like plastic when cooled. But did you know that you can dissolve ShapeLock in chloroform solvent? This allows you to do things like dip objects into it, cast it in a mold, or paint it onto surfaces to form thin sheets. You can buy chloroform online. [JN]

Deciding How Thick Your Mold Should Be

Frank Ippolito of Tested.com cautions that you don’t want the sidewalls of your molds to be too thin, but if you make them too thick, you’re just wasting mold material (and money). Frank recommends your molds be about ½g to 1g away from the piece that you’re molding. It would be best to make it a little thicker closer to 1g where you plan to zipper-cut (also called a jeweler’s cut) the mold to provide more stability, but otherwise ½g to ¾g or so is fine. [FI]

Using LEGOs for Mold Boxes

If you’ve looked at any molding and casting how-tos online, or done any yourself, you likely already know this trick, but it’s still worth mentioning. LEGO bricks make for a perfect, reusable, and resizable mold box, and nearly every hobbyist (and pro) who does casting uses them.

Reinforcing Mold Boxes

Frank Ippolito recommends reinforcing otherwise flimsy pinned-together foamcore mold boxes by wrapping them in plaster-infused bandage material. This adds strength and stability and holds the box together tightly so that the weight of the mold material doesn’t warp and blow out the mold box. [FI]

Keep Your Scale Clean

By way of Tested.com comes this little gem for keeping your digital shop scale clean. When using it to weigh and mix epoxies, resins, and the like, sleeve the scale into a gallon Ziploc bag. The bag will bear the brunt of any yuck splashed around during your working process. [FI]

Casting Your Own Knobs

On the YouTube channel Stuff I Made, they have an excellent little video showing how easy it is to cast your own knobs for projects. Basically, all you need are some silicone molds (like the ones used for candy making) and some epoxy resin. [DB]

Rolling Epoxy Putty in Flour

Anyone who has ever used two-part epoxy putty, aka “green stuff,” (which a gaming industry sculptor once described to me as being like sculpting in stale bubblegum), knows that it’s very stiff and sticky and really doesn’t want to be easily manipulated. To overcome this, try rolling it out in wheat flour, like you’re baking bread. This allows you to roll it very thin. Once it’s the size and thickness that you want, you can brush off the excess flour (and wipe or wash the rest off once the piece is fully cured).

Bending PVC with Hot Sand

On the Darbin Orvar channel on YouTube, Linn has done some interesting experiments with heat-bending PVC piping. After trying to heat the outside of the pipe to bend it, she decided to try capping off the ends with duct tape and filling the insides of the pipe with hot sand. The results are impressive. For small- to medium-diameter PVC pipe, it looks like a great way to twist and form piping into whatever shapes you desire. [LDO]