Friend of mine showed me this trick. go to your local Grocery store and ask for their empty carboard boxes. Break them open and cut them down to 4 or 5 inch strips. Get some wood 2x4'sto build a base stand. Now on top of the stand you use a 2x6 for the bottom and a 2x6 for a top, cut to desired width for your backing. Drill a hole on each side so it looks like this
__________________
:O O
__________________:

(sorry about the drawing skills)
Center the holes (represented with the O's) on each side, and do this to both 2x6's. Attach bottom to the stand you made out of 2x4's.

Now You buy some threaded rod, bolts and washers from your local hardware store. You thread the rods through the holes you made, with washers and bolts on the outside of the 2x6's. Add your cardboard ( you will need quite a bit for a descent sized backing) and tighten the bolts to compress the cardoard. Most supermarkets will be happy to give you their empty cardboard boxes. And the lumber should be cheap enough.

You can tape a target to the cardboard get creative. Once the carboard is used up you can replace it. Buy this point you shouldn't have to replace all the cardboard.


=l============l= l threaded rods
lxxxxxxxxxxxxxxxlx Carboard
lxxxxxxxxxxxxxxxl = 2x6 compresion boards
lxxxxxxxxxxxxxxxl m 2x4 base stand
=l============l=
mmmmm
m m
m m