G'day foxy, What is the actual thickness of the stainless sheet? I have cut 1mm stainless using an angle grinder with the thin 1mm blades. Didn't take long for the small cuts I made. Cut edges were fairly smooth, but needed a final cleanup with a fine file. A nibbler as used on corrugated roofing sheets is an alternative, depending on the thickness of your stainless sheet.
agree with Al regards 1mm blade on an angle grinder. It's a great way to go on straight or very gentle curved cuts.
For tighter curved shapes a nibbler can be fine but if you can access a plasma cutter then make a wooden template and just follow that with the tip. It's great for most metals. Seen it used for 2mm aluminium and other materials much thicker, very effectively.