I ran a welding shop in a former life... before marriage and kids!! We welded all kinds of bumpers up, all steel. For appearance and ease of learning, I'd suggest a MIG welder, and you can find some that use flux core wire pretty cheap, chinky made. Also, if you want strength without weight, try going with some heavier sheet metal, like 14ga or so, and have a metal shop bend it with a rolling 90* on top, come down so far, say 8", and have them bend another 4" 45* on it, and have them do it to an 8' piece. Then you can trim it down and set your own angles for the outside corners, bend/cut it off and weld it, and you've got your own bumper. Not exactly simple, but usually lighter than trying to start out with pipe. I'm not a big fan of pipe on the front, and I've used quite a bit of it..... it makes it heavy!