This model was trained on 25 images of women wearing classic-style nurse caps from the 1950s through the 1970s. Training images include paintings, photographs, and comic book panels, and using images of both white and black nurses. (I used "african" to denote black women in the training, just to keep SD from getting confused.) Use "nurse cap" or "white nurse cap" to trigger it. At a weight of 1, it seems to produce reliably nurse-like characters.

Because of the training images all being of nurses in vintage uniforms, it does have a tendency to try to put the character in a full nurse uniform. This can generally be prompted out by using "white shirt" and "white dress" in the negative prompt, and by reducing the "nursecap" LoRA weight to 0.5.

When it comes to non-women characters wearing this hat, it's a roll of the dice. I've been able to get a few OK renders, but with no real consistency. Some checkpoints play nicer with this than others, but if you run into anything truly weird, please leave a comment and let me know about the issue.