How to make window grids?
Like muillions? There are companies on the net that you can purchase kits.
The easiest way is with kits but if you really want to make your own, here's what another DIYer did to make her own. Wishing you the best.
You could cheat and use white tape for the look, looks more realistic if you apply it over something like a curtain wire. Best wishes
I would contact this company and ask about a custom order: https://www.myoverlays.com/