Similar technic like the paper snowflakes. You cut the bag into a square than fold it a few time first in a triangle then another time in half and then cut the sides and leave a core part in the middle like in the photo. There are several other versions online. Super easy. Stick them to windows or doors.
Rubbish bag spider webs
![](https://craftymum.blog/wp-content/uploads/2020/10/eZy_watermark_10-10-2020_09-33-26.jpg)