A Rail Fence is about as easy a block to make as they come. Use the colors you need/want on the outer strips and white or muslin for the center strip. Easiest way to do the block is to strip piece the three fabrics, then sub cut them into squares. A 6" finished block is a nice size. So that means each of the strips would be 2 1/2" wide and finish at 6 1/2". Subcut at 6 1/2".
Buy about 6 Pigma Pens from JoAnns or Michaels. I like a chunkier size about a .5 or .8 . Black is best. If only the blocks will be at the function, then you can mark a 1/4" seam allowance on the white strip's outer raw edges with a blue washout marker to let the signers know not to write past the line. Then take the blocks home, remove the blue marker and then heat press them to fix the ink.
Or if you have time, you can set the quilt top, and bring that to the event. No need then to mark each block's edges, except maybe on the outermost edges, if there is no border.
Here's some examples... The first one is set on point with a border. The second one is also on point with sashing and cornerstones but no border. The third one is strait set without signatures but with appliques. They all used 6" blocks.
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