I have a small workshop, and half of the roof on the southern side is lexan, so I use it to start my seeds. I prefer to work with seeds, vs, seedlings because you know what you’re getting. Too many times I ‘ve bought seedlings and they were mismarked, people switch the tabs that define the plant. Also, I start in large containers, and only transplant once. Some I plant in 10 gallon containers for the back deck. Handy, just walk out the kitchen and grab a pepper, or a bunch of lettuce, etc.
I'm getting away from the 72 cell trays for the same reason. I want to sow the seeds and when big enough, plant them out. I hate potting up. 18 to 50 cells per tray is fine. They actually make 128 cell trays. Insane.