I'm trying to create a module that, when run, makes the user be able to place a block. However, when trying to place a block in a certain direction, the newly placed block clips into another block.

--My code
local mod = {}
function round(n)
    return n % 1 >= 0.5 and math.ceil(n) or math.floor(n)
end
function mod.StartPlacingBlock(bl,p)
	local RS = game:GetService("ReplicatedStorage")
	local EU = require(RS.ExtraUtils)
	local PT = EU.GetUtility("PartTools")
	local bl = RS.Items:FindFirstChild(bl):Clone()
	assert(bl, "item doesn't exist")
	bl.Parent = workspace
	local pri = bl.PrimaryPart
	assert(pri, "item has no primary part")
	local mouse = p:GetMouse()
	local event = Instance.new("BindableEvent")
	local c = coroutine.create(function()
		print("Coroutine started")
		PT.AnchorModel(bl)
		mouse.TargetFilter = bl
		local res = true
		local ext = bl:GetExtentsSize()
		coroutine.resume(coroutine.create(function()
			mouse.Button1Down:wait()
			res = false
		end))
		bl.Box.Visible = true
		local OH = Vector3.new(0,0,0)
		local Offset = Vector3.new(0,0,0)
		while res and wait() do
			bl:SetPrimaryPartCFrame(CFrame.new(Vector3.new((round(mouse.Hit.Position.x/2)*2),(round(mouse.Hit.Position.y/2)*2),(round(mouse.Hit.Position.z/2)*2))))
		end
		print("Coroutine ended")
		bl.Box.Visible = false
		event:Fire()
	end)
	local success, err = coroutine.resume(c)
	assert(success, err)
	return event, c
end

return mod

There are no errors in this code, however:

Building off of this side of the pillar works fine as displayed in this image: https://prnt.sc/o4hbfl

However trying to build off the other side makes the block phase into the pillar: https://prnt.sc/o4hby2

I'm completely lost, please help.

AnonymousEdited