Looks wonderful KK. Tomatoes get leggy for sun, but also for having air flow. With gentle air flow or movement on them, their little stems strengthen and get thicker. I'm not sure what you have available, but mine have a gentle fan breeze all of the time that their lights are on. It may or may not help as I am indoors. But it did make a huge difference in the thickness of my stem. Even gently brushing your hand along them every time you go to look at them helps. Your baby plants look healthy and green! Amazing job KK. ( so so exciting) A little personally learned caution that your cup is transparent ( I used green water bottles when I had the experience)...roots don't like light. Could you wrap the cup in a piece of paper, tin foil or fabric to block the light? It may help. Just a thought. Might also help keep the roots cool in your high heat ( I would melt in your climate. Your my heat hero) This is wonderful to watch and see.
Thank you so much for your comment Melody. My seedlings are now full time out in the great out door of my garden They are subjected to all the outdoor natural elements except for the scorching noon sun and rain. When the sun goes down they come into the porch to be protected if it rain but not from the night breeze or wind. I guess they do get quite a fair bit of the breeze and wind. The transparency of the cup, yes thank you for bringing that up and I will definitely find a way to shield them. Thanks again Melody, it is indeed a joy to watch them grow
About what Mel said about movement and stem strengthening— I believe that this is an important aspect bringing your plantlets on. I do not use a fan system, but I do rub my hand across the leaves every time I go in and look at them, and that is frequently just like Mel.