If you were going to build a set of working pens what materials would you use? Already have 2 3/8 tubing for posts...what would you recommend for rails? Panels? Have about 40 head of angus cattle nothing too hot. Old pens are pipe with pipe railing, but calves can squeeze through. Looked at the heavy duty bull panels that you can weld (smaller squares similar to hog panels). Also looked at the continuous panels. Want something small calves can't squeeze under, through, but don't want to spend a fortune. Thanks in advance for any responses.