ChangeHistoryService

local ChangeHistoryService = game:GetService("ChangeHistoryService")
local Selection = game:GetService("Selection")

local toolbar = plugin:CreateToolbar("Example Plugin")
local button = toolbar:CreateButton("Neon it up", "", "")

button.Click:Connect(function()
	local parts = {}
	for _, part in pairs(Selection:Get()) do
		if part:IsA("BasePart") then
			parts[#parts + 1] = part
		end
	end

	if #parts < 1 then
    -- Nothing to do.
    return
  end

  local recording = ChangeHistoryService:TryBeginRecording("Set selection to neon")
  if not recording then
    -- Handle error here. This indidcates that your plugin began a previous
    -- recording and never completed it. You may only have one recording
    -- per plugin active at a time.
    return
  end
  
  for _, part in pairs(parts) do
    part.Material = Enum.Material.Neon
  end

  ChangeHistoryService:FinishRecording(recording, Enum.FinishRecordingOperation.Commit)
end)

local ChangeHistoryService = game:GetService("ChangeHistoryService")
local Selection = game:GetService("Selection")

local toolbar = plugin:CreateToolbar("Example Plugin")
local button = toolbar:CreateButton("Neon it up", "", "")

button.Click:Connect(function()
	local parts = {}
	for _, part in pairs(Selection:Get()) do
		if part:IsA("BasePart") then
			parts[#parts + 1] = part
		end
	end

	if #parts > 0 then
		-- Calling SetWaypoint before the work will not cause any issues, however 
		-- it is redundant, only the call AFTER the work is needed.
		--ChangeHistoryService:SetWaypoint("Setting selection to neon")
		
		for _, part in pairs(parts) do
			part.Material = Enum.Material.Neon
		end

		-- Call SetWaypoint AFTER completing the work
		ChangeHistoryService:SetWaypoint("Set selection to neon")
	else
		-- Nothing to do. You do not need to call SetWaypoint in the case where
		-- the action did not end up making any changes to the experience.
	end
end)

local ChangeHistoryService = game:GetService("ChangeHistoryService")
local Selection = game:GetService("Selection")

local toolbar = plugin:CreateToolbar("Example Plugin")
local button = toolbar:CreateButton("Neon it up", "", "")

button.Click:Connect(function()
	local parts = {}
	for _, part in pairs(Selection:Get()) do
		if part:IsA("BasePart") then
			parts[#parts + 1] = part
		end
	end

	if #parts < 1 then
    -- Nothing to do.
    return
  end

  local recording = ChangeHistoryService:TryBeginRecording("Set selection to neon")
  if not recording then
    -- Handle error here. This indidcates that your plugin began a previous
    -- recording and never completed it. You may only have one recording
    -- per plugin active at a time.
    return
  end
  
  for _, part in pairs(parts) do
    part.Material = Enum.Material.Neon
  end

  ChangeHistoryService:FinishRecording(recording, Enum.FinishRecordingOperation.Commit)
end)