Looking female to me. Id go 75% sure. Seen enough P. metallica to say theres a pretty good chance at female here. Though, at that size you should be able to see some dimorphism in the abdominal striping soon.
@WebBrowser hmm. I thought I'd read that ornata but not metallica could be sexed dorsally. Do you have a link showing what to look for? I'm quite certain that my son would provide dorsal pictures if this species can be sexed that way.
The male in this photo is already mature at the time so its overtly pronounced, but you can get an idea of what to look out for. Duller coloration, less defined lines/fuzzier color break in the pattern, full stripe etc. Around the 3 inch mark you should be able to take an educated guess, but in the photo you provide I do not see any fusillae present and the shape of the booklungs in line with the vent area lead me to favor female.
Here's one that someone just posted. Id bet my left shoe that it's a male. See the little V shaped dot above the line? Your's does not display this. Booklungs are also acutely angled. Id bet the right that you have a female.