Wannabe braider

Hi, I was wondering if someone out there might be able to help me? I am trying to make an 8 strand square braid mecate out of paracord. I am using 550 paracord and am concerned the cord is too thin. When I started to make it, it came out less than 1/2" thick. I was hoping for closer to 5/8". I am thinking about adding a core to it, but I am worried that if I do, that it won't come out square anymore. Anyone have any input on this? Thanks, Jessica