DIY Room treatments..How Large?????

I picked up a sheet of Owens Corning and some low profile batting material for front face of panels to "soften" the face appearance, and some Natural Needled Cotton fabric to wrap panels in, I have 4...2ft X 4ft pieces to work with, I want to tame one wall, as other has a sofa along it and a quilt rack at first reflection point. I also want to place one on ceiling at reflection point and 2 on the back wall.
My room is small, 13X20 and I wanted to know if I place one 2ft X 4ft panel in middle of room on ceiling at reflection point would 4ft across be enough width and 2 ft be enough from front to back?
Also if I cant make a tube trap, could I use more of these behind speakers? or will these be less then ideal?
As far as making tubes it seems both hard to make and also hard to purchase the right suppplies with me being disabled and on a fixed income but I do want to make the best out of what I have.
So in short, will my panel be big enough for ceiling reflection?, I will also use one on live wall to tame it down and have 2 left for back wall. and if I get one more peice, and material could I use 4 more for corners behind tower always thanks a bunch guys Regards,
If anyone would be willing to talk with me I would gladly accept, I can call to save long distance charges for help, please send me mail if any offers thanks!
No problem, Ausjoe! It took me awhile to figure out Agon's mark-up tags...just click on the link below the "Your response" box.

I haven't built any panels. I'm using a type of foam, 4" thick, with a pyramid structure that is used in studios. I've covered my back wall, to prevent unwanted rear reflections. My listening couch [also very absorbent] sits right against the back wall. I am listening "nearfield".
Any ideas on what I can use to mount the outer cotton wrap to the panel? I am just wraping the needled cotton around the ins panel and need an idea to fix it in place, staples wont work...thought about some kind of glue, or pins..or any other ideas,,,,thanks all
I've used loctite power grap, 3m 77 might do the job. Myself I would build a wooden frame around your panel, very easy to do depending on your disability you might ask a friend to help. This will make it much easier to Mount and to put a cover on. But a word of caution breathing in fiberglass is not a good thing. You"MUST" put the batting around the whole panel, then the cover. Burlap makes a very good cover but if your cotten is a nice open weave( if you can blow through it very easy) it should do the trick. I made my cover like a pillow case and then sliped it over then either sew it closed, staple 0r use brass tacks.. Good Luck.
If I have some styrofoam insulation panels in my basement from previous people here, can I use some of these for any purpose? I have enough cover material and batting material, the needled cotton is very breathable and looks great. The panels are 5/8 thick and I can cut them to any size...can these be used at all? thanks again