Cast On

I'm not referring to the podcast, although I do enjoy it (yay Brenda!). I'm referring to the Sweet Baby Cap. I bought some Plymouth DreamBaby DK the other day, and sat down last night and cast on for the hat. I didn't have the needle size, and am curious to see if the pattern is written correctly, since it has size 2.5mm needles (I know those exist, just not in US sizes) and 3mm needles. I've never heard of or seen 3mm size needles before. I'm not sure if they truly exist, or if it's a misprint. It could be like the Loch Ness monster...mythical to some, but to others, as real as can be. :)