Ha! Gotta keep it light ya know. No, I'm trying to keep a stoichiometric ration of twist shifters to trigger shifters. That and its cheap. REEEEAL cheap.

 It depends on how you count the time. I played with the design on paper (and computer) for 2 months or so, gathered/built the tooling over the winter and spring, built a previous frame that didn't quite have the angles I wanted, then with all that revised, I machined the parts for this one over the course of a week after work, then cut the frame tubes on a Saturday, Welded it on a Sunday, painted it on a Monday, assembled it on a Tuesday, test rode it on a Wednesday!

 I built the frame, and I haven't figured out its name quite yet. For now its the "maroon bike" (as opposed to some of the others laying around my place - the black bike, the blue bike, the other blue bike, the green bike...)

 At home in my shop for all the cutting and welding, and then I did the paint and alignment at work.

 how much dose a welder cost?

 Well, if you are talking about a GTA (also known as TIG) welder, those usually start around ~$2k for something decent, and go up pretty fast from there. There are cheaper ones, but they aren't something I'd recommend spending money on. Also, consumables (gas, rod, tungsten, gloves, etc.) increase the cost another $250+ to get started.