I use a 1.5" wooden ball. You can acquire these from craft stores, they are sold as doll's heads, I think. I then drill a 5/32" hole through the center of the wooden ball and another 1/4" hole half way through. I make a loop of 1/16" stainless wire rope (from West Marine) through the hole and I swage an oval onto the two ends. The swaged bit will fit nicely inside section of wooden ball drilled to 1/4" leaving a loop out the end. My wicks, which are a "four-fingered" monkey's fist not of 3/8" kevlar rope burn for 7-8 minutes without any additional absorbent material in the core. I've heard of people using absorbent material in the core, but I've never actually seen this done. To make a nice looking knot, a nice round core is required.