Algodoo

If you are on PC then here is a helpful tip to produce longer boxes

Go into the Algodoo console (by pressing the same key that has ~ on it) and type the following but replace P with the number of KM that you want the box to be.

Scene.addBox ({pos:=[500*P,0];size:=[1000*P,1];ruler:=true;})

­Then press ENTER and then the box will spawn. Note that any value that is equal to or over 1000 may crash Algodoo.