Blankets / towels so long as mom is cleaning up (changed daily at least). Pine I like when they are a bit older but I remove pups from that area to feed them as I worry about them ingesting too much pine shavings (since they are little slobs and walk thru the food!). Mine are normally transitioned outside by age 5 weeks, with a big doghouse on the deck and a step down to the grass - all fenced for just the pups. After the first day deck and bed stays very clean and all clean-up is on grass which can be hosed down often and the pups are half housebroken when they leave! I bring them indoors in the evening for play periods - but they really love their outdoor pen.
I used the printed newspapers to line the box and pen. Then I used those nice, clean roll ends for the top layers. I took a single edge razor blade and cut lengthways to shredd those rolls. Sometimes we used the paper shredder on strips of paper cut from that roll. There were times when the newspaper office had lots of free shredded paper that they were throwing away.I went to the local newspaper and asked for the "end rolls" -- it's the plain paper that newspapers are eventually printed on. It's fairly cheap. I would layer regular newspaper (with the print) on the bottom... the paper from the end rolls on top and then a few towels. Worked great. Good luck!