Fire Mountain Gems sells tons of beads and there are hundreds of companies just like them that sell any bead you could possibly need. They have a cool website and you could find any number of different sites just putting in glass beads on google or whoever.
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Looks like they are just seed and bugle beads that you can find most places at any craft store that sells beads. Here is a link you can buy them online…they even have a brand named after them…

http://www.firemountaingems.com/seedbeads.asp#MingTree
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I dont make the trees but i would see if you can find a pat catans store they have lots of things there and are very help full on this stuff this is where i go for most everything to do my jewelry.
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also try this website
http://www.firemountain.com

http://www.firemountaingems.com/
Under chip beads and rounds 3-4mm and 6mm work great with my trees. Check my site, too. http://www.d-wireguy-denver.com …. I have several instructions for different ways to make trees, too. Good luck. glenn
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A wired ming tree, which we call a gem tree is very common in the rock and gem world where we teach the lapidary arts. The best trees are made with gemstone chips, but you can certainly use any type of crystal or bead. We do not glue the stones on the wire like some do, but instead purchase the stones with the holes in them. If you would like to see a sample of my trees, you can check out my web site. I also have instructions on making a mini version in the Learning Center. Enjoy as this is a fun hobby.

Thanks,
Dana James
http://www.danasjewelrydesign.com
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Fire Mountain Gems or Ship Wreck Beads both have internet web stores.