El Chapo drip hydro

Hello VitaMan, You want to use food grade materials. If it is safe for food then it is safe for a product that you grow for consuming like cannabis. I like to use food grade stainless steel for multiple reasons, it blocks the light, it never gets old and it is safe for your product. If you are searching for a 1 time cheap fix then I would recommend aluminium foil that you use in the kitchen. Happy Growing Buddy!

Epoxy will leach out. Will it be toxic to your plant? It will depend on the epoxy you use. I would suggest food grade silicone sealant.

once the chemical reaction is done, yes its safe. The only thing that then could happen is that your grow LEDS destroy it by time if you dont give it a solid paint. It releases the softeners from the resin, just like in cheap plastic.

Yes. I would plan a strategy ahead of time to deal with the excess roots from the cube. Taking reasonable steps up in PPFD is preferable I think. I don’t know the distance your 45watt light will be vs the 300watt. But maybe you already have this process planned out?

I've kept rooted clone cuttings in plugs placed in just net pots with hydroton for several weeks(like 5+) just irrigating them twice a day before transferring them to a reservoir. It will work for seedlings too. It helps if you keep your plugs in some type of tray that helps keep your roots covered and prevents them from drying out as fast. Just don't let the roots dry out....but don't soak them either lol....really just misting the roots a couple times a day is all they need. Honestly I would worry more about stretching keeping them that long under a 45w. I'd run it a little extra close.

Not ideal. You really want them out of something so small. It'll start small. Small main stem, as it can't build root arms and expand. And that's what forms bigger main stems. In turn gives stronger larger plsnt base. A better Base tends to give better finish or makes it easier imo Prep is crucial I think. And 2 weeks of week stems vs 2 weeks of even starter 2l pots. Well I know which I'd pick. Also. If you're using hydro. Or soil. You want a bigger area for roots and root arms to branch out.