You will need...
N.B. You want the PVC to be as thick as possible.
While it helps to be dexterous with a scalpel on PVC, this is one of my quicker, more straightforward tutorials. Whoever said you can't get the look of vibrant opulence without keeping it simple?
About 2 hours.
Badge it up
Use this template (simply copy, paste and print it)...
...to trace a flower shape into both pieces of PVC and cut them out with a scalpel.
Punch holes where you want the ends of your brooch clasp to go on the top layer. Decide where you want the bottom layer to go, place it underneath so that it overlaps but is not completely covered by the top layer, mark where the holes should go to match the top layer, remove the bottom layer and punch the holes.
Paint over the two flowers with clear nail polish or resin to harden and thicken the material.
Stick the two layers together with craft mount, making sure the holes are aligned. Undo the clasp on the brooch and put the two ends through each hole - you might need to widen the holes with the scalpel and coax the two ends through. Fasten the brooch.