Rebuilding calipers is a bit more of struggle than it might seem, largely because the pistons don't come out or go back in easily. There are some special tools - tongs to remove the pistons and plyers to install the dust caps - but you can do without. You can push the pistons out with air pressure but this is a bit tricky also. The dust caps can be pushed on with your fingers once you get the hang of it. The whole operation is just awkward because of the shape of the caliper. It's a good idea to have the MB CD on the job. And of course when you're done you need to bleed the brakes. Figure several hours per axle for a first timer.