OK, I played with this and did a crappy job because I was working fast and not really measuring my horizontal lines. I was more or less roughly trying the technique I decided would work best. I apologize for the slop but I'm not interested in trying to make it perfect. It was actually more work than I anticipated.
The entire pattern is based on the stars. I used the Polygon Tool to make a star which I then copied 5 times, changed their colors and positioned. 2 of the stars (left) are just for masking.
I placed these in a group.
I then started making my horizontal lines for masking.
Which I masked out by adding a layer mask to the star group, making a selection of the lines.
Then I made Red stripe layer and a Blue stripe layer. Added layers masks to both.
Then the final set of horizontal lines used for masking out the blue and the red lines.
The rest was just about making selections, going from layer mask to layer mask and using the Brush Tool to mask out areas I did not want on the red and blue stripes including the shapes of the stars. I will admit that I would have a very difficult time explaining this process..................so I'm not going to try.
You need to resource Ps videos on making multiple selections. This can also involve inverting some selections. It will be a challenge.
For example: Here I have made a selection of the stars and then added in a selection of one of the stripes. This allows me to erase/mask using a layer mask, areas that I want to remove from the red and blue stripes.
