The Queen's Round Metal Hat

Every queen needs a round, metal hat, or "crown".  This one is technically a 'coronet' as it does not close in the middle.  The queen is Titania, queen of the faeries, daughter of Titans, and fittingly, her crown is made of titanium.  The parts were designed using Autodesk Inventor and fabricated with a CNC waterjet cutter, in the traditional craftwork of olde.  At TechShop.

Traditionally, faerie crowns are forged in a volcano.  If a volcano is unavailable, you can purchase .035 sheet titanium from a number of online suppliers.  For a 22" circumference head, you will need a sheet 7.5" x 19."  Titanium is not essential to the construction, you can use steel or aluminum.  That is, if you fear not to offend the faerie queen. 

  -Titanium sheet, 7.5"x19"x.035"
  -Blow torch 
  -Welder (TIG or Spot Welder)
  -Work holding equipment
  -Welding gloves
  -Metal Cutter
  -Autodesk Inventor or another 2D vector design program.

The three parts of each side consist of two bezier curves.  These can be rendered in Autodesk Inventor as splines or arcs.  I have added extra thickness to the points where they will be welded that will be ground-off later.  The circumference for this piece will be 23", so each half spans 11.5".  

If you do not have access to a CNC cutter or a faerie, the parts can be cut from sheet metal using hand shears or an equivalent stationary shear.  

Start by laying the separate pieces out in formation and figure the precise angle at which they will be joined.  If you can, make a mock-up crown from cardboard to get the shape right.  
  Some tacks can be made with a spot welder, though for edges this thin, a precision TIG welder is called-for.  Titanium can often be welded without filler if there is enough contact area.  
  All points can be welded at this time except the front center, where the two ends come together.  This must be done after the metal has been bent into roughly the final shape.  Do not weld where the pieces cross in the middle.  The parts need to move freely when being bent and can be tacked afterwords.  

The parts are flat, and they must be curved.  I cut an oval from oak to achieve a perfectly symmetrical ellipse.  Using a blowtorch, heat the metal until it is bright orange.  At this point, it will hold most of the curve you bend it to.  The bend does not need to be hyper-extended since the curve will be closed in the front.  The unjoined pieces on either side will have to be bent separately. 
 You need only heat those parts and bend them until they don't resist.  Uneven heating will produce an irregular curve, so keep your eyes on the orange metal and keep the flame moving.  

Now, with a nearly closed ellipse, the front can be clamped together and welded closed.