The Finished Whale’s Tail (pattern below).

Front view.

Back side.

Directions

Cut out pattern.
Sand metal lightly with 400 grit.
Glue pattern to metal. I use a glue stick.
Saw out metal.
Finish edges with files and sandpaper.
Round any sharp corners if necessary. Here’s a little video on rounding edges on metal.
Use a dapping punch, either in pitch or on a stack of magazines, or a sandbag, and dome both fins.
Anneal.
Using round nose pliers (put tape on them or dip them in plastic dip to protect the metal), round up the tips of the fins. I rounded mine away from the back so that the points wouldn’t scratch the wearer’s skin. Here’s a video on Rounding Edges on Metal.
Curl bail towards the back, either using round nose pliers or the stem of a dapping tool.
You may need to punch down the area between the fins. Lay the dap, length-wise, between the fins (on the sandbag or in the pitch), with the rounded sides facing up. Hammer a thin dapping punch, laid lengthwise, into the space between the fins to create a thin depression.
Final finish. Remove any scratches. Polish.

Here’s a short video (website only) on altering a patterns size – if none of the patterns, below, are the size you’d like.