Hi man,
so after reading through your journal I have decided to jump in to share my thoughts. You are doing great so far, your plants look all vital and promising.
I like the cupboard with car window foil, that's so much better than aluminium foil, but even paper or white paint is better than alu foil. And the dull side of aluminium is more reflective than the shiny one.
As for the fans- I say do not put push-pull fans, rather use them only to pull. If you have small hole near the push fan then the filter will not work as some air can escape. Also make sure your intake hole is as big as the outtake or even bit larger. I've made my own carbon filter for 16 bucks you can check it
here. And it works super smooth with 2 quality high CFM (Arctic F12 continuous) 120mm pc fans pulling the air. I've never saved on pc fan cost and I have fans in my PC that are still running silent after 4 years.
In my first grow I used closet as a grow box. I did remove the top shelf in mine as the airflow was bad. I mounted everything on the ceiling using screwable hooks and ropes for light (light on hooks not on the picture) and filter and consoles for my 12V output for fans.
Also, look how much light you lose because you do not have any light reflectors around your bulbs. My cheap suggestion is- buy hard paper bigger one like A3- 420mm x 297mm make cones of it and place it on the cord on your lights. Or do not even make cone, just cut a circle, cut it to middle and put it around your cord, secure with ductape- done.
Hope this helps. Have a good one.