I've used something like this:
You can find black ones as well of that's useful.
Turn it diagonal and you can get wire fences or lead lined windows
Its made from plastic cross-stitch mesh; https://www.amazon.co.uk/Darice-Number-Mesh-Canvas-13-Inch/dp/B007YVJFKY/ref=sr_1_5?dchild=1&keywords=cross+stitch+mesh+plastic&qid=1608974289&sr=8-5