I usually write on the cups too. Last year I bought several packs of plastic plant markers marked down real cheap. I was so excited to use them this year. Potted up some of my seeds and put the markers in... only to discover they're too tall for the lights!

So my plan is to wait till the seedlings are lower from the light as they grow, then put the sticks back in. Writing on the cups it is, once again.

I use wooden “craft sticks”/tongue depressors. I toss them into the compost bin when I’m finished with them at the end of the season.

I use vinyl mini blinds. A cheap one from a discount store is less than $10 and you can get hundreds of markers cut to whatever size you need. They aren't fancy but they do the job. i can't remember who I learned this from but have seen it used many times.

I use the shorter plastic stakes and mark them with permanent marker. They fit under the lights in the tiniest cell paks. They're about 3 and a half inches. I save them each year in alphabetized zip loc bags.

Just last week I tried this method. Rinse out a small milk jug and slice it up with scissors to create markers in the length you need. I haven't put mine to use yet.

I use mini-blinds and/or plastic yogurt containers cut into the right size strips and write on them with permanent marker.