3D Printable Case / CNC Fanless Heatsink


We have a 3D printable case available for the SiFive HiFive Unleashed board. It was designed in FreeCAD and is available under free licenses.



Happy hacking,



Hi, Jeff

Thanks for the case design. I printed it, but I struggle with attaching the clips, they are too thick to bend/snap-on. I used PLA filament and I think it will break before I will be able to snap it on as the walls on this design are pretty thick.


Hi Jeff,

Few more remarks on the case, it has no venting holes, so probably prolonged run in the case might create problems. And the USB cable doesn’t align well with the case, it means by pluging the USB the whole board lifts by 0.5mm or so. This means if the board would be firmly secured to the bottom you wouldn’t be able to plug the USB to it. Top has cutout for the USB connector, but the bottom needs cutout as well and the size might vary depending on the make of the USB cable and how thick the end of the connector is.


The clips are quite tight. I did some in PC-Max and they were too rigid to use. I printed one in PCTPE that worked perfect.

My case got up to ~30C or so. More air flow would be good.

I’ll check on the USB cable, I didn’t notice a problem on mine.

We’ll work on improving the design in the next revision.




The github repo has been updated with some new clips which make work better for you.

The ones we did in PCTPE turned out really great.

Happy hacking,


Hi Jeff,

That should probably be mentioned in the repository, PCTPE is strong BUT flexlible, which explains why everything is so thick (having semi rigid case even when it’s flexlible). While PLA is hard and brittle (it will shatter/break before bending even tiny bit), I would say many people use PLA/ABS or other filaments (carbon/wood) etc… I think if your design is made to printed with flexible filament from ground up, it should be mentioned so people will know.

Thanks for the updated clips, I will try the second sets of clips and will report back how they went.

The USB cable margin could be noticed differently with different cables, so probably I had bit thicker cable than you, but eitherway the design should allow for both. I used something like this:

While something like this might not have the issue:


The new file names should help:


I have a bunch of different USB cables, I’ll give those a test.

By the way, to clarify, just the clips are printed in flexible PCTPE. For the case, we’ve been using PC-Max (Polycarbonate by Polymaker). We’re testing some Taulman Alloy 910 (very strong nylon) too.

Thanks for your suggestions!



Yes the names are grand, I hope I will have them printed today. Will let you know tomorrow as I lend the case so I don’t have it with me.
What you are going to do with the case?!
It already looks so thick and maybe even too robust :slight_smile:

So I printed the clips with 1 perimeter wall which made it bit bending, but much less robust, but when I tried them on the case, they were too lose, they can be put on, but they rattle and probably will get undone very quickly. I might try if the rigid design is tighter and if 1 wall will bend enough to snap-on, probably they will break first before bending, but we will see.

Ya, it is super robust. With PC-Max and PCTPE you could run it over with a car.

I also added rubber feet (bumpers). The ones I used are available here:

Vibration Mounts (aka SDP/SI) Part # V10R87-B08130

McMaster Part # 95495K22

We’ll look into other ways to lock it down. This design makes it easy to pop on & off, but seems to work better with flexible materials than rigid ones. Taulman Alloy 910 nylon is also really good.

I’m not getting nylon filament just to print one case, so I will stick with filaments I have (I have stash of about 5-6kg of PLA filaments anyway). Running it over with a car might be bit overkill :slight_smile:

We have a new bottom that should work better for larger USB cables. See here:


A new top is forthcoming as well. Feel free to file issues in github, if you like.



Amazing timing, going to print it tomorrow so I will have it ready for the Barcelona in hopes I will get it signed by the guys.

We’ve added a heatsink that allows for fanless operation. Untested. Files are in the github repo under CNC/. Some pics here of the one we made on a Tormach CNC: