We find that Granular M will compact on its own with normal traffic. However, compacting will hold the aggregate in place better and help to mitigate damage from heavy rain, as well as providing a more aesthetic surface. If you are doing a small area, a small walk-behind gas plate packer will work. Ensure it is graded and raked prior, as raking after will be much more difficult. If it is a larger driveway or parking area, packing with a large ride-on roller will put the finishing touches on the driveway. If the material is on a hill, compacting it immediately is highly recommended, even if you have to drive on it several times with a vehicle.