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)