I have been using several large white towels for drying my fiber paper. Before using them wash the towels several time in hot water with bleach and don't use fabric softener to remove the flint. I lay the prints between the towel on top of one another. When the prints are almost dry I move them out of the towels. Another way is to buy heavy canvas; place the prints between the canvas and the canvas between the towels. Remove the prints when they are almost dry. Good luck.
When stationed at a Navy base I could put fiber prints between clean sheets on my bed and weigh them down with a blanket. In a few hours they were dry and fairly flat. Storing them face to face and back to back in tightly packed boxes completed the flattening process.