Straw and hay are probably the most common materials used to line nest boxes. They are fluffy and will offer a cushion for the eggs to be laid upon.
What also helps is to make the bottoms out of the same hardware cloth used to cover openings in the coop and run. The 1/2" x 1/2" stuff. Tack it to the bottom. The dust and small stuff will fall through to the floor below (won't work for an external box). To this end, some use a plastic milk crate as the nesting box, with an opening cut out in the front, or you could also put it on it's side if you then cover the opening with a 4" board or strip of plywood. Make that removable and the milk crate can be pulled out for cleaning. Cleaning out old bedding and also cleaning in the event of a broken egg . But milk crates are only 1 foot square. Nest boxes for the larger breeds a lot of us keep should be bigger than that. More like 14 to 16 inches deep.
At least one 100 year old design used nest boxes built in pairs.......wood sides and hardware cloth on the bottom, that was also removable. It sat on a shelf and would slide out. In case of a really bad mite problem, they held it over a fire to burn em off the wire bottoms. But again, removable so it can be cleaned.
And of course if this is an inside nest box, it should have a sloping roof so the birds cannot perch / roost on it and leave their droppings behind. They will if the top of the nest box is flat and level.