I haven’t used it, so I can only suggest alternatives: 18mm, 36mm extension tubes and the extremely hard to find 110mm f4.5 macro.
Currently, I have them packed away, so the numbers may be off, and I don’t actually have the 36mm extension tube, but that would be good for macro. I find them a bit awkward to use, though. The 18mm is more versatile, but the 36mm is better for macro.
The macro lens is excellent, but you have to take into account a 2 stop loss of light at max magnification. That makes it basically an F7 lens. If you use flash, it isn’t a big deal. It does 1:1 macro.
That being said, if you’re going for the bellows, what I suggested may not be useful.