How To Mold and Cast Foam Props!

Our very own Frank Ippolito shows you how to make simple silicone molds to cast and paint foam replicas of props like shop tools! We go over the moldmaking process and show how self-skinning expanding foam can make great-looking stunt props for your projects.

Comments (31)

31 thoughts on “How To Mold and Cast Foam Props!

  1. YES! This is the video I’ve been wanting since I started watching Tested stuff. I’ll be trying this with my sons this year. Thanks Norm and Frank!

  2. Great video, but damn, that’s over £250 / $300 worth of silicone!

    Edit: Correction – I was looking at Mold Star. Mold Max is more like £200 / $250 for 12kg

  3. Yeah, I really wanted to try mold making, but the cost of silicone is really prohibitive, especially if you’re an amateur and are likely to screw up at first. Are there any casting materials that are cheaper?

  4. yes, i understand this. maybe try smaller things first, or doing brush-up molds to save on silicone. plenty of less expensive ways to do it, i was just doing it a quick way.

  5. yes, i understand this. maybe try smaller things first, or doing brush-up molds to save on silicone. plenty of less expensive ways to do it, i was just doing it a quick way.

  6. Hi, love the video, I follow ur work closely, you explain everything so well, will you ever make a video step by step molding a full head (silicone/latex or foam) mask how to mold i and the best materials to use, Ive been wanting to see one and you do the cleanest molds ever lol, so pls if you will let us (me)know thanx

  7. Yeah, that’s fair enough, I appreciate that it’s probably cost effective on the scale that you do things in your shop when you take into consideration the extra time of more involved methods. Hope it didn’t come across like I was taking a dig, was just an observation 🙂

  8. it’s an acrylic paint. It doesn’t flake off? Would inks work or would it be too translucent? What are some paint options for foam.

  9. in the UK the stuff they use on US videos is expensive, I generally use polycraft Silicone its cheaper and still reliable.

  10. Thanks for the quick reply Frank! I’ll have to see how available it is here in Canada. But either way, I’ll give it a try. Thank you

  11. great video, thanks! Lots of little useful tricks to learn from!

    Could you maybe do a video or provide some tips on various stirring/mixing techniques (by hand, machine, etc) and vacuum degassing to minimise bubbles? I keep having problems particularly with translucent/clear PU rubber resins. The resins I have are often quite viscous and have short work times (3-5 minutes), so that there is not enough time to get the bubbles out in vacuum. Warming them up makes it more liquid, so that helps, but then the work time is even shorter… I’ve seen vacuum casting machines that mix under vacuum, but they’re way too expensive…

    Do you have any tricks how to mix it while avoiding to get bubbles?

  12. Love watching these videos. They give me soo many ideas, many of which I would need a maker space to do them in. I think I have the space out back for trying this out, once the weather improves.

    One question that does come to mind:

    Is there a pourable foam analogue to LD45/Karrimat to make props out of, once you have created the silicone mould to pour it into?

  13. Neat video. Face off has awoken an interest in things like this for me.

    That limp axe made me smile 😀

    I’ve never made any mold. But couldn’t you clamp some straight mdf boards on the bulging sides with woodwork clamps? It’s not like you cant reuse these materials for similar or other projects. Does this sound like a good or bad idea?

  14.   the golden is lower viscosity. Once a base of nova is on there to bind to the foam, other acrylics stick pretty good

  15. Really liked that small pin technique to stabilize.

    I’m a big supporter of Smooth-On and their support of Tested.

    Brick in the Yard has quite a few videos with molding and materials like Smooth-ON.

    I’ve tried both and prefer Smooth-on, but in do find Brickintheyard materials can save you some money if cost is a critical issue. BITY is a group of prop guys in Texas selling foams and casting materials and have some fun videos online.

    Smooth On and Reynolds Supply really can’t be beat for service and support. Smooth-on has some good demonstration videos but without commentary to contextualize, more a-b-c process steps. However videos like Franks here on Tested really do a lot to fill in the gaps.

  16. Frank, what did you wipe on the board surface at the very beginning of the video? And what units are you using for your dimensions when measuring the box to calculate silicone? My niece got some alginate mold material from a local art store. Would that be acceptable if you only want to make one casting from a mold? I’ve made one mold of a tool for fun and had all of the problems you describe. Mold bowed. Too much compression deformed it during casting. Silicone leaked. Make mistakes, find new videos that tell you how to avoid them. Implement and try again. : )

  17. Hello, you used to write great, but the last several posts have been kinda boring… I miss your great writings. Past few posts are just a little out of track! come on!

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