I just pick up some black pipe from Lowes or HD. determine the height you want then pick up those lengths some t- fittings.
this has been hit by 22lr.-- 45 acp -- 7.62x54. I built it about 8 years ago and use it when training new shooters( and yes I 've hit it ) cost me about 50 bucks but the years and hits have proven that it was worth it.
Isn't ricochet a factor?