You could also use an old EF 35-80 kit lens (they came on old rebel film cameras) & remove the front element. This gives you a crazy "zoom" macro that I believe goes beyond 1:1, but with no auto focus or working distance. If you just google "Canon 35-80mm macro mod" a bunch of things come up. You could but that lens for next to nothing.
Yup, got one of those also, but I prefer the 50/1.8 with extensions. The modified 35-80 is almost a microscope. I realize saying this might be tantamount to sacrilege to 'L' aficianados, but stopped down the 35-80 takes acceptable daylight photos also (as a normal lens)........not every shot needs a 24-70. Think I paid 25$ for mine.