I have made ID tags with white plastic butter knives and a sharpie pen. Not really fancy or classy, but inexpensive and effective.

Helen.

Great idea! Thanks!

Many of us who winter sow use cut up window blinds and write on them with pencil or paint pens. We find that Sharpies and other markers fade before the winter is over. I also use plastic knives. When the plants are larger they are hidden by the foliage and they are easy to find. I find that the blinds get brittle and break easily after awhile. If you go to the winter sowing forum and search markers you should find other suggestions.