Emancipation Grill (grill.lua)

local list = { "sand", "slime_ball" }
local ra = 3
local function main()
    while (true) do
        local c = commands.exec("testfor @a[r=" .. ra .. "]")
        if redstone.getInput("left", true) or redstone.getInput("right", true) then

        else
            for _, i in pairs(list) do
                commands.exec("clear @a[r=" .. ra .. "] minecraft:" .. i)
            end
        end
    end
end

main()