Larry,
Three cam follower bearings, one horizontal axis and two vertical. I machined the housings from aluminum.
I applied to a RFQ and was one of three pick to make a proposal. It was a pretty involved job for me, logistics, paperwork bla bla.
Your portfolio is your biggest asset, but you also have to communicate your ideas on paper, not necessarily drawings, just give them an idea of what you want to do.
Start small and local, if they know who you are they are more likely to award you the job.
There are many call for artist in the Seattle area and they have a thriving art community. If this is your ambition you should be able to land one, just be prepared for many rejections.
Lynn Basa wrote a very informative book on the process "The Artist Guide to Public Art"
Personally I'd rather just put the stuff in my yard but, I gotta feed the children and moma needs a new pair of shoes.