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I have an old notebook computer that works just fine, but the outside of the lid is badly damaged and needs to be replaced. The screen and wiring are fine, so I only need to replace the housing that is exposed to the outside world.

What is the best filament for an impact-resistant printed housing? Should I consider other options that may prevent damage to the internal components? Are there any alternatives with cosmetic benefits?

Edit: Since I was asked, presume I may be willing to buy a new part to upgrade or accommodate a new filament type.

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  • $\begingroup$ Are you asking about material type ie. PLA, PETG, PC... or specific brand of filament? Tell me some more about your setup. What materials are you capable of printing with your hot-end/printer? $\endgroup$
    – John Marangola
    Commented May 3, 2022 at 17:27
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    $\begingroup$ I tagged the question with "filament-choice" because I believed that signaled material type rather than brand name. Are different brands within the same filament type so significantly different that I should beware? $\endgroup$
    – when squared equals a negative
    Commented May 3, 2022 at 23:01
  • $\begingroup$ @whensquaredequalsanegative: For some materials, the material name is more a broad class of polymers rather than one specific one, so things can vary by brand. But I think you're right to just be asking about material types and I'm not sure why that wasn't clear to John - it was clear to me. $\endgroup$
    – R.. GitHub STOP HELPING ICE
    Commented May 4, 2022 at 1:50

2 Answers 2

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For casings I use a combination of TPU and PETG or PLA. PETG shell gives it rigidity and TPU gives it a bit of impact protection. So corners and inside layers of TPU within a hard PETG or PLA shell (shell has no corners).

I haven't had a problem with either but obviously PLA won't withstand heat very well, so it depends on environment.

For a laptop case you'd maybe want to do it the other way around with the outside shell of TPU and inside layers of PETG for rigidity.

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If you just cared about impact resistance of the housing itself, the clear choice would be TPU, which would be basically indestructible. However, the housing is there to protect what's inside - not only from impact, but from stresses (e.g. bending) that could break it. This means you need a material that both provides rigidity and avoids breaking easily itself.

If you were doing an old (90s or earlier) style laptop case that's a tank, I'd actually say yeah, go with TPU 95A or higher (98A or so if you could get it) and add some reinforcement ribs/stiffeners. This stuff can be quite rigid at 100% infill, and it will hold up fine to heat, abrasion, even most chemicals. But if this is a modern slim style case, a small amount of material needs to provide a lot of rigidity and that's not going to work.

PLA actually fares really well here in some ways - it's one of the most rigid printable materials, and very easy to get good bonding. If you check for example CNC Kitchen's strength tests, you'll find plain PLA usually coming out on top of most comparisons. However, PLA doesn't handle heat well, which might rule it out.

ASA, ABS, or PC is probably your best bet, but I don't have any experience with them so I'll leave the part about them as something for another answerer to write.

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  • $\begingroup$ I wouldn't trust PLA: it's strong but brittle, which makes for low impact resistance. $\endgroup$
    – Mark
    Commented May 3, 2022 at 23:59
  • $\begingroup$ @Mark: That's what people say, but if you actually go and do the tests (or look at data from someone who does), it seems it's better than most of the alternatives. Somewhat related: I have tiny PLA gears operating in places where the PETG ones I tried first kept breaking. $\endgroup$
    – R.. GitHub STOP HELPING ICE
    Commented May 4, 2022 at 0:02
  • $\begingroup$ Strength is not the same thing as impact resistance. People frequently conflate the two, but the difference is why we armor things with steel, not glass. $\endgroup$
    – Mark
    Commented May 4, 2022 at 0:05
  • $\begingroup$ @Mark: Can you find test results where PLA fared worse either way? I know Stefan tested both and I believe the PLA did surprisingly well, but I may be misremembering. $\endgroup$
    – R.. GitHub STOP HELPING ICE
    Commented May 4, 2022 at 1:46
  • $\begingroup$ ASA, ABS and PC are probably stronger and more resilient, but they also out gas toxic gasses when printing, so you'd need to vent that safely. $\endgroup$
    – user10489
    Commented May 6, 2022 at 23:52

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