function laser()
local laser = Instance.new("Part",player.Character)
	laser.Size = Vector3.new(1,1,1) --makes the laser
	laser.BrickColor = BrickColor.Red()
	laser.CanCollide = false
	laser.Anchored = true
	laser.TopSurface = "Smooth"
	laser.BottomSurface = "Smooth"
	local mesh = Instance.new("CylinderMesh",laser)--mesh
	
	--do raycasting.
	local start = player.Character.Torso.Position -- the starting position
	
	local ray = Ray.new(start,(mouse.Hit.p-start).unit*300) -- ray
	local part,pos = game.Workspace:FindPartOnRay(ray,player.Character)
	
	local dis = (start-pos).magnitude--the distance between the mouse hit and the start
	mesh.Scale = Vector3.new(1,dis,1) -- scaling
	laser.CFrame = CFrame.new(start,pos)*CFrame.new(0,dis/2,0)--this is the issue
end

I could make this easily work without the cylinder mesh, but it looks cooler hen cylindrical.

whenever I call this function, it makes the parts on my head, here's a visual of what I mean

AnonymousEdited