When we made it for our school auction, I used Kona cotton and washed it and did not starch. I ironed on freezer paper cut a little smaller than the block and allowed each child to only draw on the freezer papered fabric, made it so much easier to maintain the seam allowance.
I would obtain a box where my pieces would lay flat if mailing to just one person.If mailing out individual blocks to each person I would fold it in quarters and include a note to please iron out creases before signing or fold it to where the signature area stayed flat. I would be sure to mail everything in baggies with a mailing address in it JIC.