i used gallon water or rinsed milk jugs, before started using small cardboard boxes and plastic totes. just put several layers on bottom then pine needles or shavings. dont use straw or moss as straw will absorb and hold moisture and breed black mold, bacteria, and mites ect, also poke or cut parents and young. moss will hold to much moisture and can rot eggs just from that and tangle babies or be eaten (usually wont hurt though if you have nothing else). usually the milke containers were too small for enough nesting material and parents to keep warm or cool enough except small roller or tumbler breeds. i just use large cheap dollar dog food bowls that have rim that wont tip or get scooted around and then if bred communally just put two nest bowls, with at least foot between them and sides of on a high board wide long enough for all nests. wall, foot of space, nest bowl, foot of space, nest bowl, foot of space, taped on cardboard partition, then foot of space nest bowl ect.. the at least foot or more is important as otherwise the young and adults may just poop all over the place and not be as easy as scraping the nest boards. the two nests is easiest and best way to maximize breeding each pair and stopping fighting, as each hen will want two nests, as she will want to lay again two weeks after first pair hatch, and then cock will take over most of parental duties of first pair of young, will hen does most of care of second pair of eggs. this is of course only if you have healthy birds and ive found a good deal of that factors on space per pair, as supposed standard breeding cage 24" x 24" for pair will burn out your birds from only one pair of young, while my cheap 36" x 30" 16" work really well and keep breeding strong until i stop them, though ideally 40" x 40" x 40" would be ideal.