How do I change the properties of an entire model?

Insert this in the model filled with the parts and follow the green text in the script. Oh and +1 dis :D

print("Tochi Was Here")
for index,part in pairs(script.Parent:GetChildren()) do
    if part:IsA("Part") or part:IsA("WedgePart") or part:IsA("CornerWedgePart") then do
        --do stuff from here :
        part.BrickColor = BrickColor.Green()
        part.Material = "Grass"
        --to here :D                 
    end
    end
end

Those 10k parts are in a model right? No one leaves TEN THOUSAND PARTS in Workspace ._.

function Scan(model,tab) -- Scans through EVERY object in (model)
    if not tab then tab = {} end
    for _,v in pairs(model:GetChildren()) do
        if v:IsA("BasePart") then
            table.insert(tab,v)
            if #v:GetChildren() > 0 then Scan(v,tab) end
        end
    end
    return tab
end

parts = Scan( Workspace.Model ) -- Edit 'Workspace.Model' with your terrain


for _,v in pairs(parts) do
    v.BrickColor = BrickColor.Green()       -- Edit the parts
    v.Transparency = 0
    --etc
end

Here is where I got info from.. http://wiki.roblox.com/index.php?title=API:Instance/GetChildren

Anyways, according to that, if you read it there is a script..

local children = Workspace:GetChildren() -- edit this
for i = 1, #children do
    print(children[i].Name) -- edit this
end

All you need to do is change it to include the model Workspace.(ModelName):GetChildren()

then delete print and put what you want to edit about them inside there.

I believe this should work, but I can't be 100% sure on it because i've never used it yet.