Ask MAKE: EPS foam

Craft & Design

Ask MAKE is a weekly column where we answer reader questions, like yours. Write them in to or drop us a line on Twitter. We can’t wait to tackle your conundrums!

Dan writes in:

How are big closed cell polystyrene bocks made? I’ve seen them 12″ square and about 8′ long.

Expanded polystyrene foam (EPS or Styrofoam) is made from pellets of polystyrene, which is a plastic made from crude oil. The pellets are expanded in a steam chamber. You can find these pellets in this form inside most beanbag chairs. To make solid objects, they use steam molds that fill a chamber with the pellets, then steam fuse them into custom packaging, foam drinking cups, etc. Here are a few videos I found on the topic; one’s on Planet Green, the other one is a segment on Discovery’s How It’s Made:

Polystyrene is lightweight and good for protecting valuables in shipping, among other things, but it’s not biodegradable. It can, however be recycled. I found a video on Planet Green where they turn styrofoam packaging into moulding for your house. Neat! Also, don’t forget to check out the Wikipedia page on polystyrene foam.


Discuss this article with the rest of the community on our Discord server!

Becky Stern is a Content Creator at Autodesk/Instructables, and part time faculty at New York’s School of Visual Arts Products of Design grad program. Making and sharing are her two biggest passions, and she's created hundreds of free online DIY tutorials and videos, mostly about technology and its intersection with crafts. Find her @bekathwia on YouTube/Twitter/Instagram.

View more articles by Becky Stern


Ready to dive into the realm of hands-on innovation? This collection serves as your passport to an exhilarating journey of cutting-edge tinkering and technological marvels, encompassing 15 indispensable books tailored for budding creators.