Are you asking me? :) I am not sure... In any case 3M fine line should be available at Auto Body supply places. Be advised that is is not as thin as Tamiya tape. Tamiya tape is about as thin as it gets.
Avoid the green 3M fine line at all costs. it is no good for model use. The blue stuff is what you want. Note that it is a "plastic" tape, not like the blue 3M paper masking tape that is sold at home supply stores.
Tamiya tape may be hard to find. Depends on how well stocked your LHS is. Ordering it online is probably your best bet. I live in California and Hobby shops here do carry it, but I have no idea about your area.
If you need to make curved lines, I would suggest that you do what I do, which is cut Tamiya tape down into thin strips. Use a straight edge and some sort of hard, smooth surface (I use CD cases) and cut it into the size you think will make the bend you need. For 1/72 models you are probably going to have to do this no matter what tape you use. 3M fine line even at 1/16" will not make very tight curves. It is meant for use on 1/1 cars after all... You can then fill in the area behind this line that you want to protect with more tape. You could use your 3M tape for this, you only need the thin stuff right at the edge :)
Cheers,
John