I'm looking to make a portable ramp to move risers and sound shells, (3-400 Lbs) etc from gym floor to stage (3 foot high stage). Not sure how long it "needs" to be for a decent angle. Rim on side to keep things from rolling off. Maybe even strong enough to move a piano up and down, (not essential.) Would like to make it folding and tip it up on wheels. for easy transport when not in use. Anyone have a design or pictures of such they could provide? Much appreciated. Thx!