Just a guess, but I'd say a 2D with heavy pressure.
This is the tip I use...very similar to the wilton 2 D.
Yes,with heavy pressure and move your hand very slowly for the frill to form.
Oh welcome to the CC ShamsD. I'm so glad you're here now. I've always adored your your work of art.
I have been a member for some 2 yrs now but always forget to to log in.
I happen to check my stats on my flickr a/c and noticed loads of views coming from CC.
Clicked on the link and brought me to this page.
Thank you all for your reply.
ShamsD I love your style.. your work is amazing!!