The cardboard works good, even in the garage, if you're planning to spill something like ATF all over the place. I had a wood creeper, didn't work very well. A buddy gave me a nice 6 wheel creeper with an adjustable headrest, it eases a lot of strain on the neck muscles. I oiled all six casters, laid on the creeper on my concrete driveway with a slight grade, and rolled right down the drive, out of control, until I cleverly stopped myself by ramming my head into the floor jack handle.