Ok DeeBoy, I got you. Here it is step by step with pics. And I provided you the new and improved version, lol. So....
1. Cut cup in half
2. Cut slot out of middle of cup
3. Cut bottom completely out of clear cup
4. Cut bottom out of outer cup but leave enough to not let the clear cup slide through
5. Put cut-in-half cup (this is obviously where your dirt goes, lol) inside clear cup.
6. Put clear cup/cut cup inside the outer red cup
That's all it takes. Now, last time, when I first posted this, I also took the time to poke many a hole all around each cup, I was thinking for air flow, just like in a smart or air pot. But that takes a long time, you have to do it carefully to not split the cup, it's really a pain in the ass, and honestly it's not necessary for seedlings or as long as it will live in the Dixie cup. That's why instead of doing the bottoms as I did on the first try, with lots of holes, I cut the bottoms out completely. That way drainage is supreme. So no holes necessary. Plus I found on the first try that the holes you poke in the bottom have the plastic edges sticking up or down inside or outside of the cup, and either one is problematic - holes sticking up inside the cup compromise the drainage of the hole, and those sticking out from the bottom make it drain unevenly. So I personally have canned the hole poking. But if you choose to poke holes in the cups, you gotta do all three cups or there's no point. Anyway, that was the main upgrade to the system, lol. Just put in your dirt, even out the slot you created so that you can see dirt up and down the slot on both sides of the cup, and you're ready to go. It will pay off in two gigantic, useful ways that will really help you zero in the proper transplant time. Everyone, including me, transplants too soon. I learned that on grow one, and reading
@Emilya. Read her stuff on How to Water a Potted Plant. Follow it religiously, and you will develop root balls like you won't believe. I begin her watering method in the Dixie cups, as soon as the plant has two sets of leaves or so. And the results, again, you will see when you transplant, are astounding. You will pull out a perfectly easy root/dirt ball that fills the entire cup without twisting all up on itself cuz you will be able to SEE it. And here's an important thing that Emilya taught me: DON'T judge when to transplant based on seeing roots at the bottom of the cups. DO transplant when you see roots top to bottom on the sides in the slots you made. That's cuz the taproot and associated roots will hit the bottom pretty quickly, and it may appear to be transplant time. So FYI. The last suggestion I have is to get some mycorrhizae, any good brand. For one grow I got the salt shaker sized one by an unsponsored company (GW). Dust your holes with the mycorrhizae before you transplant. When you get to the point of transplant I can help if you need. But basically you just shake the dust into the hole like you would put salt on your food. Try to get it to stick a little to the moist sides of your hole. This will make your roots take off like mad, trust me. And if you combine that with Emilya's watering method, I think you will do really well.
Hope that helps. Grow on! Pictures step by step to followl, and good luck with the grow!!!: