Well, *this* Hollow Cube was a poor choice in fabrics.  For the 3D Illusion to work, you need highly contrasting fabrics.  I thought my dark was dark enough, in relation to the medium ... but ... the execution proved otherwise.  My dark and medium look too much alike and the illusion is lost.

I just now remembered that I have a piece of red plastic ... a product that was marketed as a "Ruby Beholder".  You look at your color choices through the red filter and it strips away the color, leaving only the hues? shades? <whatever> ... the *contrast*.   I need to start doing that to make sure that my 3 choices will result in a good hollow cube block.  Now, where the heck did I put that thing?

I'm still making little houses for my quarantine quilt and sadly it is getting bigger than I intended.  I was hoping for a wall hanging, but it's too big for that now.  Surely, it can't get couch size! 

I love that Ruby Beholder gadget ... it's helped me make many a decision ...

Hope you find yours!

Hi there!

I'd bet on at least couch size !!!

Have a great day and stay safe.

The ruby beholder is indeed an awesome tool. Now that you bring it up I have no clue where mine is either. 

If your Ruby Beholder developed legs and ran away you could go to Office Depot or Staples and purchase a red plastic "report folder" which will accomplish the same thing.

I have a pair of "Sew Red" glasses (with red lenses) but apparently they are no longer on the market. Here's a silly posting on the Missouri Star Company's website saying they don't have them ..

https://www.missouriquiltco.com/shop/outofstock/16657/sew-red-glasses/-/sew-red-glasses

I seem to remember reading somewhere that you could take a B&W photo of something to see the color values better.  (Or, just take the photo and then do whatever you have to do in your photo program to show B&W only.)  I will admit, I have never tried it, but it might work.    

Of course, on Amazon they have everything.  You could find a pair of red-lens glasses on this page.  There are a few pair under $10.

https://www.amazon.com/s?k=glasses+red+lens&####

Thanks for finding those, Jonna.

Those would be harder to lose, ladies.  LOL

Pirate (PIRATE_SR) said:

Well, *this* Hollow Cube was a poor choice in fabrics. 

The illusion still works!