you can also get cheap, flat white, 1/4" drywall tha's ready to go with a primitive 2x4 frame from home depot or similar.

don't forget to drill some drainage holes in the paint bucket.

i use 5 gal buckets after they germinate and veg for as long as it takes to show sex in 1 gal pots...then transplant f's into the 5 gal's. starting them in the bigger buckets will shorten the time for them to get rootbound...which will happen anyway after 6-10 weeks in the 5 gal's. not a prob if flowering by that time...