well, i dont know about the other guys, but how i make mods you go into notepad or whatever script programs you have then create the dimetions and shape like this
env_obj 1: This is the number of the object, in order as number one, number 2, number three etc.
shape box: This is the shape of your object
pos 1.0 -8.0 3: This is the position
color 0.5 0.5 0.5: This is the color, color doesnt matter but you can change
it using the standard colors, red, green and blue
rot 0 0 0: This is the Rotation
sides 10.0 0.1 6.0: This is the density
material steel: This is the type of material your using to make the object
mass 1: This is the weight of it
#END 1: Type this after the first object is completed, if second object type #END 2, if third type #END 3 etc.
pos 1.0 -8.0 3
The first number you see is the position of the object, whether you want it left, or right
The second number you see is the secondary position, if you want it far foward or far back.
The third number you see is height of the object, ajust if you want it high or low
To do these you have to change the number.
1.0 = one meter
0.75 = 75 centermeters
8.0 = 8 meters.
color 0.5 0.5 0.5
The first number you see is red, ajust it with the more or less numbers you choose.
The second number you see is green, ajust it with the more or less numbers you choose.
The third number you see is blue, ajust it with the more or less numbers you choose.
When you have finished your mod it should look something like this