Simple script. How do I resize the parts?

How do I resize an object correctly? The object doesn't go through other parts, instead it gets flung up.

c1 = script.Parent.Parent.c1
c2 = script.Parent.Parent.c2

function onClicked()
    for i = 1,30 do
        c1.Size = Vector3.new(c1.Size + Vector3.new(0, 0, 10.06))
        c2.Size = Vector3.new(c2.Size + Vector3.new(0, 0, 10.12))
    end
    wait(5)
    for i = 1,30 do
        c1.Size = Vector3.new(c1.Size + Vector3.new(0, 0, -10.04))
        c1.Size = Vector3.new(c1.Size + Vector3.new(0, 0, -10.10))
    end
end

script.Parent.ClickDetector.mouseClick:connect(onClicked)