Custom Chat Local Script

local rep = game:GetService("ReplicatedStorage")
local chatted = rep:WaitForChild("Chatted")

local uis = game:GetService("UserInputService")
local deb = game:GetService("Debris")

local par = script.Parent
repeat task.wait(.1) until par:FindFirstChild("Frame")
local Box,Chat = par.Frame:FindFirstChild("Box"), par.Frame:FindFirstChild("Chat")
local Focus = Enum.KeyCode.Slash -- "/" key

uis.InputEnded:Connect(function(input,x)
    if not x then
        if input.KeyCode == Focus then
            task.wait()
            Chat:CaptureFocus() -- focus to the textbox
        end
    end
end)

Chat.FocusLost:Connect(function(Enter)
    if Enter then -- check if Enter was pressed
        chatted:FireServer(Chat.Text)
        Chat:ReleaseFocus() -- release textbox focus
        Chat.Text = "" -- clear textbox
    end
end)

chatted.OnClientEvent:Connect(function(String)
    if typeof(String) == "string" then -- check if its a string or not
        local temp = Box:WaitForChild("Temp"):Clone()
        temp.Parent = Box
        temp.Visible = true
        temp.LayoutOrder = #Box:GetChildren()
        temp.Text = String
        deb:AddItem(temp,300) -- clean up
    end
end)