Quote: Send a PM to @lpatelski , she has numbered beads made of a rubbery material that she sells for $15 per thousand with free shipping. 100 each of 0-9, each number is also a different color. They fit perfectly on 4" zip ties. I currently have 65 chicks aged 2 weeks to 6 weeks, tagged them all last weekend just to keep track. These are about the best "non-invasive" method of tagging I've found, and these particular beads are the best of many options. Most are cubic hard plastic beads, these are rounded soft beads.
Just make sure you change out those zip ties as the chicks get bigger. That's why I use numbered wing tags. They're hard to see unless you've got the bird in your hand, but you don't have to change them out as the chick grows. Somewhat more expensive but way less hassle over time. I do wait until the chicks are 5-10 days old before I wing-tag them. There isn't much room for the tag before then.