So you would like to make your own flexible LEGO strips to stick to windows and other surfaces. Adafruit has shared a guide that shows you how to do just that. These strips are 3D printed with a rubber like material (NinjaFlex 85A) and stick to glass surfaces without additional adhesives. You can attach LEGO blocks on top.
You will just need a 3D printer, Ninjaflex filament, and tweezers to complete this project. More info is available here.