Design wall drama

I put the gray and white squares on the design wall.  Some feel neither gray nor white.
They were supposed to be 12" square. As you will see in the picture, some are off a bit and some are way off.  (These were collected from my mil's guild members)

Can you see the square that is a wee bit oversize?!

And which square missed "white" by a few shades!

These are my connecting fabrics.

 I've got some ideas on what to do as 'filler' to connect these squares. 

I just don't want to make this a long difficult process.

You can't see the sparkle here but it's metallic polka dot. 

I may make a sparkly border.

Here's hoping you find sparkly challenges of your own today!