Thanks Kathy and Dunster!
I think I have finally found the ideal ruler for this set of quilt blocks. I found it here:
http://crafts-sewing.hsn.com/olipfa-...588127_xp.aspx
I may be purchasing this soon.
There is another ruler just like it at 12.5 x 12.5 under the Donna Dewberry Rulers.
Diane