Here's my first block. Maybe I read all y'all's directions wrong, but it measures nearly 13" square. I cut my strips a thread larger than 2.5" and sewed with a scant 1/4". I think my next set I'll forget the scant 1/4" and hope that helps.
I had a really hard time picking fabric. I finally threw all the FQ's I collected into a bag and made my husband pick out 18. He kept saying, "You do it." But I told him I can't. I know how the different ones feel!!! My blocks will all have a polka dot, a stripe, and a neutral, plus three "surprise" fabrics. I was cutting for the fq swap and had enough to use some for these. Hense the polka dot and stripe.
Hope that's ok.