i built the one showed in rcca and it works great. ther materals will cost about $25 (depending on which grade of ply you use)

1. you will need: a 4X8 foot of .5 inch peice of ply, two metal hinges, 6 feet total of small link chain, wood screws

2. cut the ply in half

3. install the hinges

4. the length of the chain will determine how steep the ramp will be. use a wood screw on each side of the ramp to attach the chain to the sides of the faces

now go BASH!!!