Roughly the size of a CD, probably smaller... it's in rubber now so I can't measure it, and it's so cold the usual eight hour cure is likely to be 24 plus...
I did wonder if anyone could enlighten me about greenstuff. I use milliput and adore it, but it's been a right pain putting fresh uncured milliput upon cured, it hasn't always stuck and then needs a fiddly amount of superglue. Does greenstuff adhere to itself better do you think?