This is a simple heart shape, I designed it so that it could hold a Neopixel strip inside, and the hole is to thread the strip through so it can be powered and controlled from the outside. I suppose you can also mount your microcontroller inside of it, but I haven't tried that yet.
Note that the photo shows an entire 1 meter of neopixel strip crammed inside, but the effect wasn't actually great so I ended up just lining the edges with the strip and then letting the rest hang outside. And yes, I put the heart on a Pusheen.
This is my first design using Fusion 360, and I figured this would be a good base for anyone looking for a simple heart shaped container.
Because this is my first design, I haven't gotten a hang of the orientation and sizing yet, so when slicing in Cura, I scaled the base to:
And scaled the cover to a uniform 96%.