cardboard. yes or no?

Ive been growing 4 plants for the last 2 months. For my grow room im using an old XL size dog crate and i have cardboard mounted to each side of the crate so it creates a nice grow box. on the inside i have the walls covered with reflective tape and then of course all of my lights, fans, etc. during the day the temp never gets over 85 and at night it may get down to 75. this is my first grow and im pretty much a "newb" when it comes to growing and my friend recently told me he heard using cardboard was a terrible idea. so can anyone give me advice? whats the bad thing about using cardboard?

it can make your plant mold.Why,idk lol thats jus wat i heard but ive seen alot of cardboard grows
and they all look fine jus dont burn ur house down lol but how big are they?

thats what i think whenever i see cardboard grows iv had a regular light fall over into clothes before and start a fire

ill take a picture of my plants when i get home to show you how big they are, and btw im using cfl bulbs...incase that matters when it comes to a cardboard grow box

just get some 3/8" - 1/2" plywood at Home Depot and make it legit. Build it on top of the dog house if you want haha. Will be easier to hold fans/lights and such...

i think cardboard wouldnt be a good thing

Carbohydrates are good in the flowering stage, i personally use AN Carboload during the whole flowering period.

Where those pics...i wanna seeeeeeeeee. IMA GONNA POST PICS OF MY BABIES TOMORROW.. (DURBAN POISON) 1ST WEEK INTO FLOWERING!

sorry i havent posted the pics yet, ive been busy putting together a new grow room, so ill post pics soon as i get a chance