Building tool part going through the floor?

(THIS IS A REPOST)

Hey, so I'm making a very basic btools system, and I need help where placing the object makes it go through the baseplate or other objects. Server

local tool = script.Parent

tool.PlaceObject.OnServerEvent:Connect(function(plr, pos)
	print("recieved msg")
	local block = Instance.new("Part")
	local health = Instance.new("IntValue")
	block.Size = Vector3.new(4,4,4)
	block.Anchored = true
	block.TopSurface = "Smooth"
	block.BottomSurface = "Smooth"
	block.Name = plr.Name.." Block"
	block.BrickColor = plr.TeamColor
	health.Name = "Health"
	health.Value = 3
	health.Parent = block
	block.Parent = workspace
	block.Position = pos
end)

Client

local plr = game.Players.LocalPlayer
local tool = script.Parent
local mouse = plr:GetMouse()

tool.Equipped:Connect(function()
	part = Instance.new("Part")
	part.Size = Vector3.new(4,4,4)
	part.Anchored = true
	part.CanCollide = false
	part.TopSurface = "Smooth"
	part.BottomSurface = "Smooth"
	part.Parent = workspace
	part.BrickColor = plr.TeamColor
	part.Transparency = .5
	mouse.TargetFilter = part
	
	mouse.Move:Connect(function()
		local mouseX = mouse.Hit.X
		local mouseY = mouse.Hit.Y
		local mouseZ = mouse.Hit.Z
		possiblePos = Vector3.new(math.floor(mouseX), math.floor(mouseY), math.floor(mouseZ))
		part.CFrame = CFrame.new(possiblePos)
	end)
	
	tool.Activated:Connect(function()
		local mouseX = mouse.Hit.X
		local mouseY = mouse.Hit.Y
		local mouseZ = mouse.Hit.Z
		tool.PlaceObject:FireServer(possiblePos)
	end)
end)

tool.Unequipped:Connect(function()
	part:Destroy()
end)

I'm experimenting with photos, so try this: https://lh3.googleusercontent.com/-Yq1yIgMoCb4/XsMUkfda2-I/AAAAAAAAFF0/O_Q0Crxkpponl4Cbj9ue6oMIBhEhom0dwCLcBGAsYHQ/s0/wack.png

Also, pos is mouse.Hit.p

Thanks!

Ok, I found a post on the devforum by Stickmasterluke and I used his template and made this script. It isn't the best in the world, but it works so that's all that matters xd

local player = game.Players.LocalPlayer
local tool = script.Parent
local mouse = player:GetMouse()
local RS = game:GetService("RunService")

local target = nil
local pos = nil
local norm = nil

local MAX_PLACEMENT_DISTANCE = 2000

function doFakeMouseStuff()
	local ignoreList = {part, player.Character}	--game.Workspace:WaitForChild("BaseStore"):GetChildren()
	local mouseRay = mouse.UnitRay
	local newRay = Ray.new(mouseRay.Origin, mouseRay.Direction.unit * MAX_PLACEMENT_DISTANCE)
	target, pos, norm = workspace:FindPartOnRayWithIgnoreList(newRay, ignoreList)
end

tool.Equipped:Connect(function()
	part = Instance.new("Part")
	part.Size = Vector3.new(4,4,4)
	part.Anchored = true
	part.CanCollide = false
	part.TopSurface = "Smooth"
	part.BottomSurface = "Smooth"
	part.Parent = workspace
	part.BrickColor = player.TeamColor
	part.Transparency = .5
	mouse.TargetFilter = part
	
	RS.RenderStepped:Connect(function()
		doFakeMouseStuff()
	end)
	
	mouse.Move:Connect(function()
		if part and pos and norm then
		doFakeMouseStuff()	-- Just to be cetain that the data is up to date.
		local endPos = pos + (norm * (part.Size*.5))
		part.CFrame = CFrame.new(math.floor(endPos.X), math.floor(endPos.Y), math.floor(endPos.Z))
	end
	end)
	
	tool.Activated:Connect(function()
		tool.PlaceObject:FireServer(part.Position)
	end)
end)

tool.Unequipped:Connect(function()
	part:Destroy()
end)