I know I'm a bit ahead of the game (the deadline is next August), but I got excited about the project, and finished it!
The flyer calls for a "star-themed block". I guess it might be cheating a little, but I went with an image of the ISS. I've enjoyed watching it zoom by a few times, and I always describe it as looking like a very fast, very bright star.
I based my image on the patch for Karen Nyberg's mission to the ISS. It came out looking a little moth-like (which is appropriate enough), so I call it Lepidoptera ISS.
It took me a while to figure out how to do the stars. I would have liked to mimic the style from the patch a little more closely, but I couldn't get an effect I liked. So I used two different circles that my machine does automatically and added crosses in straight stitch.
The dimensions are 9.5" x 9.5", which is just a bit too large to fit into any of the envelopes I have. I was quite pleased with the solution I came up with for posting it.
I have a watercolour pad with nice thick sheets of about 9.75" square, so I took two of those to make an envelope. I didn't want to risk the fabric sticking to the tape though, so I added "cuffs" of standard-thickness paper. I was trying to figure out how to tape it all together without getting any glue on the block, when I realised that the cuffs don't actually need to attach to anything.
So I sat the block on one watercolour sheet, popped the cuffs on the four sides and sat the other sheet on top.