How can I make a model spawner tool?

If you have the tool, the decal, everything, and you just need the script, you can do the following: You will need a normal script. Put it at the tool. You can type

--Also, I am not scripting you the events when the player clicks with the tool, etc..
plr = script.Parent.Parent.Parent -- script is in the Tool, tool is in Backpack, backpack is in the player (at game.Players.Player)
isplayer = workspace:FindFirstChild(plr.Name)
if isplayer ~= nil then --Making sure the player's model is in the workspace
    isplr = isplayer:FindFirstChild("Humanoid")
    if isplr ~= nil then -- If 'Humanoid' exist:
        --And there, you can get player's position with the following code:
        pos = isplr.Torso.Position --isplr.Torso.CFrame is also can be used
        --And now you just spawn the model at a little bit away from the player. I am not going to script that for you.
    end
end

I hope I didn't made any mistakes, I didn't tested it because I can't script a tool, but I think that it works. You got the player's position, you can now do anything. I hope this is what you wanted.

you can use Clone() and MoveTo() to accomplise this local Model = game:GetService("ServerStorage")

local WorkspaceModel = Model:Clone()
WorkspaceModel.Parent = workspace
WorkspaceMode:MoveTo(game.Players.Enzo341.Character.HumanoidRootPart.Position + Vector3.new(0,0,-5))