How to make a tool change a players avatar

So I have this model that I want to weld to a player’s arm when they click the tool but how would I make it so it only works for 1 player?

To confirm you want to make it so only one user can USE the tool that gives changes to the user’s avatar?

I want to make it so anyone can get the tool but it only changes the persons avatar who used it.

You could give each player a tool, and then check if a value is enabled so other player’s can’t use it.

local value ='BoolValue')
value.Parent = game:GetService('ServerStorage')
value.Value = false
value.Name = "toolUsed"

after you want to check if the player uses the tool:

tool.Activated:Connect(function() -- when the tool is clicked
 if game:GetService('ServerStorage').toolUsed.Value == false then -- checks if the value is false
   game:GetService('ServerStorage').toolUsed.Value = true -- like a debounce script kind of
  -- avatar editor script here