need help-how to build sound absorber, deffusive

Since I moved to the new room, my system sounds so bad that I don't listen to the music anymore. It realy hurts my ears. My new room is hardwood floor, I put a good size rug in front of the speakers, put the speakers on the stands, and some live plants behind the speakers. It helped but the low and the mid bass are muggy. I know there is a lot of room accoustic material that could help, but I can't afford them. Does anyone build their own bass trap and sound deffusive? Would you please show me how to build one and tell me what materials to use and where to purchase them?
Thanks.