I designed this for my daughter, for fun and to fit the aesthetic of her room better than any other PC case I could find. It's relatively small ( 6-ish liters ), and supports a mini-itx motherboard, an SFX power supply and a 140mm fan.
Be warned that this is not a polished design, but a rush job before Christmas - it's not guaranteed to print well (as can be seen in some of the photos) and took some rework/hot glue to hold together properly.
Requires some motherboard standoffs and screws to attach the motherboard and PSU. Fan was mounted in a hurry using hot glue!
If you want to print this, remember to account for the shrinkage of the material you are using - for my first attempt in PETG, the screw holes for the motherboard didn't line up.
This was made using Tinkercad, so if you'd like to modify it I've shared the original design here: https://www.tinkercad.com/things/8fnZ4A4FfDg
I also shared some pictures of this earlier on reddit here: https://www.reddit.com/r/sffpc/comments/zsy0l4/more_pcs_should_be_cute/
The author marked this model as their own original creation.