You take a cylindrical foam core, mount it to a mandrel and turn to the desired shape. I do not have a good quality cork in a full wells configuration to weigh against but I do in a half wells. The half wells cork weighed in at 15.6 g. Not a lot of difference but still lighter. You can get that lighter still by going to lighter density foam. I am currently using 6lb foam and a person can use 4 lb. As far as extra strain on the rod, the skin is more rigid than cork but the core is not so there should be little or no extra strain. This would only come into play if you had a blank that flexed all the way to the butt section. I would think that a rod designed for casting distance would be a moderate fast to fast action rod depending on casting stroke would not be bending to the handle. In fact depending on line size, many rods have an independent fore grip that is placed above the regular handle to hold on to help land the fish. That foregrip will put more strain on the rod than one of these grips. I learned how to do these from several sources. RodMaker magazine V10 issue 4 and V11 issue 6 cover it. You can also get a tutorial (no Pics) on Riley Rods website. They also have the all the supplies you will need.