The best part about macramé is that you can totally buy it or DIY it; both are affordable options! One of our favorite modern macrame how-to's is last year's great tutorial for pot hangers on the Skinny Laminx. We personally think that would look spectacular using neon rope or twine.
Macramé doesn't just have to be for holding up a plant or two. In the post "Nice Knots: Macramé Made Modern" you see it used in furniture and accessories. In "Modern Macramé", we see Sally England use it in a modern way with room dividers, wall hangings and headboards. We also love Tamara Maynes' Macramé Owls.
And of course, Etsy always has plenty of items with a DIY feel without the DIY headache (if you're no good at knots):
1. Grey macrame plant hanger with paper beads $28
2. Handmade Spiral Macrame Plant Hanger $14
3. Dark gray macrame single plant hanger $10
4. Macrame Plant Hanger Vintage Style $12.50
5. Macrame Plant Hangers Vintage Style Trio $30
(Images: as credited above)
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If you're hanging them outside, how do you keep them from swinging all over the place when there's wind or a storm?
these are cool too: http://www.cinchhanger.com/photos.php
To answer your question Pi, macrame is strong and can withstand most weather conditions. Safety outside is more dependent on what you hand it on. Make sure you have your plants hung on something strong. Since plants get heavy very quickly they don't blow all around. Add the pots they are in, the wet dirt, sometimes decorative rock on top of the soil and the foliage itself.
Hope that helps