Advice for USB dongle enclosure

[bitwrangler]

I'm working on a USB dongle adapter designed for a niche audience. I've reached the point where I need to figure out how to encase the device in a cost-effective manner without sacrificing quality. The adapter is comparable in size to a very small USB flash drive or a YubiKey. My plan is to use a 3D-printed, two-piece shell that snaps or glues together around the circuit board.

So far, I've tried using PLA for the 3D printing, which is functional but doesn't have the premium look I'm aiming for. When I try to improve the finish with a bit of sanding, it ends up leaving unattractive white marks on the PLA.

The SLS Nylon option looks and feels better, although it has a slightly rough texture that seems acceptable. I'm leaning toward using the nylon material for the final product.

I have a couple of questions:

1. Are there any disadvantages to using nylon for the enclosure that I should be aware of?
2. Are there any other materials or techniques you'd suggest that might give the product a soft, rubber-like feel?

I appreciate any guidance you can offer.

[ataradov]

You can try to use Plasti Dip to get the rubbery surface you want. And in that case the base plastic does not matter. You can even try to not use any plastic at all and just dip the whole PCB.

[abeyer]

I've also seen people attempt using multi-filament-head printers w/ a combination of a rigid material for the structural core and an outer layer of tpu... the results looked mixed, but might be something to try if you're up for an adventure.

[dferyance]

I love nylon as a 3d printing material but it has an important limitation; things don't usually stick to it. So if you go nylon, you may not be able to coat it; or at least no durable coating. Best you could do would be some kind of sleeve over it.

Synthetic rubbers include TPU TPE and silicone rubber. Silicone is easy to mix and coat but i'm not sure on how to get the best adhesion. I've used PVC pipe primer to bond TPU to PLA which worked pretty well.

[microbug]

The white mark problem with PLA (and many other plastics) can be fixed with a heat gun. Just be careful not to heat it up too much.

[c64]

You can try to order it from a professional 3d printing service.  I remember watching something on YT there someone ordered some 3d prints on JLC (or maybe pcbway?) - quality was nearly like a molded plastic. For the size like yours, it would be probably under $1

[mathsquid]

For something this small, you may look into desktop injection molding. Crafsman has some good videos on it.

[Kosmic]

Did you try matte filament ? The matte finish will remove a lot of reflection and layers disappear a little bit.

Ex: PLA VS Matte PLA


You could try an enclosure with a mix of matte filament and TPU for the rubber part.

[keep_hope_alive]

I've found that PLA+ or PLA Pro has a nicer finish than PLA. 

You can do acetone vapor smoothing to get a smoother finish with minimal effort once you have the setup. 

[Mechatrommer]

i will avoid PLA any days, it will disintegrate in a matter of 3-5 years. use ABS if you have to, or other more exotic materials like nylon or TPE? (i havent tried). for small small things, MSLA and resin excels. but cheap resin will crack itself as well in a matter of weeks. so i still need to find the right formulation and brand... ymmv.

[Kosmic]

i will avoid PLA any days, it will disintegrate in a matter of 3-5 years.

When used inside, I never seen PLA change that much over time. I even tested with a high resistance meter and years old PLA parts still measure in the POhm range.

Might be the quality of the PLA used or a drastic difference in environmental condition? The printer might also be the cause.