Safe Materials

[ThatOnePossum]

I was looking for tank decor and I had the idea that a mini rope bridge might look nice in a tank. I’ve since rethought that, since a wobbly bridge wouldn’t be too nice to jump to, but it got me wondering if there are any ropes that are used commonly for birds or small mammals that aren’t safe for reptiles? What are some materials that I need to avoid?
(I know about soft woods being dangerous, but haven’t found a ton else about dangerous materials)
Edit: Would a little rope bridge be safe? I just kinda assumed the gecko would fall off it.