perfekt small grow - what is needed? What a perfekt light needs or should have?

.25 m^2 -- Are you growing autoflowers, photoperiods or plan to do both? photoperiods have the highest demands due to 12 hour operation needs. To get 35-40 DLI in .25m^2 you need a light that can produce roughly 225umol/s PAR. For 18hour operation, you'd set it to 67% power. Beyond that specification, just make sure the build quality looks sturdy. Good heat sink etc... Any light with the lm301 diode as it's primary white diode can be spot-checked for accurate specifications -- light makers lie as easily as they breathe. that diode should be powered at .2watts per diode, anything more means it falls short of advertised claims. compare to samsung.com for accurate info. if over-powered understand that it will not meet what samsung.com says. That's the end of the world, but reduced longevity and increases heat and costs more to run pound-for-pound produced. Just don't overpay for something runing the diodes hot and over-promising specifications at a premium price. If they go cheap on diode count, the light should be cheap, too. If a light has 200umol/s PAR, that too is probably enough. The exact maximum DLI you can give is variable. It depends on Temp, RH% and atmospheric levels of CO2. 225umol/s PAR should be safely at or above 'max' for most contexts. A mother plant does not need 'max' DLI. You can give a bit more than half (20ish DLI) to keep a plant alive long-term. This may just take a bit of trial and error to figure out the minimum you can give without fucking up the growth pattern and still being able to take healthy cuttings from it... Material options -- angled aluminum can make a sturdy and light frame. Poly film (aka panda film) is a cheap thing you can wrap around it. Easy to cut out holes for exhaust/intake etc... Corrugated aluminum is another good option - these things come with all sorts of connectors and accessories, but also more expensive. Framing wood is generally cheap and strong enough. Some adhesive velcro strips can hold the poly film closed. if you diy it, just make sure it's more than sturdy to hold whatever weight you put on it. For this size, it might be best to find some cheap tent for less than 50 USD. The equipment for a 50x50 will be light, so their cheap poles are not a problem.