In reply,I find the challenge fun because I can weld my own tubing at work.I also can create and machine all my own flanges as I took Tool and Die in college.So for me it is fun because as I work on my project I'm helping a few friends do the same thing as well.The more I do the better they'll turn out.I also find it more convinient because I'm in no hurry to finish it so I can scavenge the junkyards when I have time or take my time and blueprint,layout and machine custom parts the I need with care and attention to detail.