18 would be a little uneven unless you did it 4x4 with one block in a top corner and one in a bottom corner as a border. This would make the top about 72 x 72.
Hope this helps
Hugs
April

18 12'' blocks would be 3x6? So that would be 36x72'' plus borders, right? I'm thinking I'll make two, too...

I would so love to do this, but being a beginner, I think I will wait for the next round, but will be watching this thread for sure!

Oh cool, cross-posted and I didn't see it until now. Nice idea, too.

Or perhaps 4x5 if I make a couple of extra blocks for each one? I don't suppose there is a quilt law that says boomerangs can't have your own blocks in it? :lol:

Craftsbyrobin I'm a beginner, too!!! Maybe change your mind? :-D

LOL No law at all and sometimes you need to.
Hugs
April

Cool. :-D

Would it be a good idea for me to send my F8s in envelopes big enough to put a 12x12 block in? Just wondering whether people tend to reuse envelopes to send the blocks home...

(Excited, excited! I've cut my fabric and I have plastic bags... did I post this already?!)

Wow you are ahead of me. I did pull 24 batiks last night for one of them, but haven't got the others pulled yet, let alone them washed, pressed and in envelopes, but I definately plan to have them at that stage before we get our lists, I want them hitting that mail as soon as possible. If we have to make 35 its going to take all the time I can muster.
Muriel

LOL Salmon
You do not have to worry about the envelope being big enough to be reused.
This is a very exciting swap-I have my fabric picked I just have to wash cut and stuff lol
Hugs
April