The folded frame is actually for a dodger; no bimini but some days would be nice. If the ends were pot metal, don't think they would last long. One of those times "marine-grade" may be a meaningful attribute. Aluminum might work, but usually there are some parts under stress to keep the fabric taught, so the strength of SS probably useful. This was made by Thurston in RI for the PO.

Our old Freedom had a bimini with straps which were a pain. I modified it to hang off the starn rail with a tensioning rod between the ribs.