Keyloop got all messed up on the first and second prints. Strung right over where the hole should have been.
Cleaned up the first two and printed a third with tiny supports that came out better:
Discussion
And here's the old one that curled.
Not sure if it was the design or me leveling up my 3d printing skills, but the green ones I just printed seemed to hold their shape. I'll assemble them tomorrow and see how the compare side by side.
Try turning your fan speed down or off and your bed heat up for the first few layers. Fast cooling seems to be the cause when mine do that.