[amsat-bb] cross boom?

In putting together my antenna,?? (144-432)I need something to use as a horizontal- cross? support boom. What would be the best length, and,? what would be the minimum length,,,? would 6? ft separation be OK?? To minimize problems, should I mount one beam horizontal, one vertical? Does it matter which one, is? which way?

I doubt I can find a fiberglas boom locally,,,? what else could I use?? or, where can I order a fiberglas boom?

thanks Bob W0DXZ