So here we go: enter layer blending options of our letter ?A? layer Instead of telling you how to set blending options I will just let show you. But remember that layer FILL OPACITY ? must be set to 0%.

Aqua pure illustration 

Aqua pure illustration

Aqua pure illustration
  


Aqua pure illustration

Aqua pure illustration

Here is our result ? I'm quite satisfied with it.

Aqua pure illustration