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Don't know what NICK makes but he has a great reputation!
The bows are made out of 1/4" ID steel tubing.
You will need (1') of solid steel tubing (you will have plenty for practice!) for the many connections from tube to tube, and finished bow to body.
These are cut roughly 3-4"s +/- sections. Then each solid piece is cut down on one end like a DULL pencil point to slide up into a matching tube. (Grinder works just fine!)
There are only a total of 4 tubes.
This is only half the story - sorry - easy to make, simple to do, IF you have a pattern.
When you do get started make sure the bows are as tight and touching,(the top) as you can get to make sure the top is tight.