How can I make each part touched only once using debounce?

You can have a variable for each part called, for example, "enabled". You can default the variables to true. In the Touched event, you can check if the variables are true using if statements. Then, inside of the if statements, after the rest of your code, set the variables to false. This way, the code will only run the first time the part is touched. Your code would look something like this:

local enabled = true

part.Touched:Connect(function()
    if enabled then
        --code
        enabled = false
    end
end)