How would I make an elevator loop up and down with While True do?

I know you can make button elevators, but is it possible to make an elevator that goes up until it hits a part, and goes down until it hits another and continues that cycle?

--I realize this would have something to do with a while true do loop, but what would the script look like? (I am sorry I am fairly new to scripting in RBX.Lua as a whole but want to create an elevator that will just contiguously loop up and down for a place.

Oh, sorry I didn't read your question so I made a bad script :P

el = Workspace.ElevatorPart -- Assume these blocks are here...
top = Workspace.Top
bottom = Workspace.Bottom
up = true
down = false
bodypos = Instance.new("BodyPosition", el)
bodypos.maxForce = Vector3.new(math.huge,math.huge,math.huge)
bodypos.position = el.Position
bodygyro = Instance.new("BodyGyro", el)
waiting = false -- you can add waiting
el.Touched:connect(
function(hit)
	if hit == top then -- You can add waiting by removing all the comments before waiting in the function below
		--waiting = true
		down = true
		up = false
		--wait(2)
		--waiting = false
	elseif hit == bottom then
		--waiting = true
		up = true
		down  = false
		--wait(2)
		--waiting = false
	end
end)
game:GetService("RunService").RenderStepped:connect(
function()
	if up and not waiting then
		bodypos.position = bodypos.position+Vector3.new(0,0.1,0)
	elseif down and not waiting then
		bodypos.position = bodypos.position-Vector3.new(0,0.1,0)
	end
end)

Hope this script helped :)