I built a target before with wood frame and all thread for the press, and didn't want to deal with all that. So I did this instead.
I cut the area carpet into 12" widths, lined them up end to end, duct taped the ends together and started rolling. Roll away from you while small to keep it tight and, when it's big enough, roll toward you while giving it a shot with your knee every quarter turn. I have ratcheting ties on it now, but I will replace with plastic banding once I get it a little bigger. Works great and took about an hour.