I had a little shop time this afternoon and this is how it went.
I cut the sink supply in 3" pieces. and am ready to start the construction. Two 20" pieces are overlapping the center piece 4". I drilled a 3/8" hole at the end of the center piece and inserted a piece of the plastic tubing in it. Clamping the three pieces together before drilling the holes to tie them together insures the holes line up. I drilled 1/4" holes and put a piece of 1/4" dowel in it. Using wooden nails seems a good idea because I was cautioned not to put magnetic material in the loop. The shoulders created by the side pieces support the cross bar.
Maybe tomorrow I can put the lower section together.
looking good so far.