For MomoCon I had created a Mary Poppins costume to wear. For the parrot head umbrella, I used floral foam shaped and hot glued to an black umbrella. Unfortunately, floral foam isn't strong enough to stand up to a con, so it didn't last the day. I want to reprise the costume, but really needed to fix the umbrella. This is what I came up with.
I started with a block of "regular" styrofoam from Michaels/Hobby Lobby.
I cut it to shape and started to cover it with regular wood putty (from Home Depot).
After I let the wood putty set for about 15 minutes (just long enough to be somewhat firm), I added the "feathers" with a toothpick. I didn't worry too much about perfection as once the wood putty dried, I'd be able to sand it down and "fix" anything that needed fixing.
I repeated that for each side (except the bottom!), letting the putty set for at least 12 hours before I went to the next side. Then I sanded, repaired, and started to paint.
Once I'd finished painting, I carved out a small area in the styrofoam underneath (which I did not putty) for the head of the umbrella to fit into. I then used epoxy to affix it. Once the epoxy dried, I used a clear coat of acrylic paint to "seal" it all in.
Not a quick project (took about a week given time for the putty and epoxy to set), but not too hard either. The umbrella cost $5 from Dollar General. The putty was approx $8 from Home Depot. The styrofoam I had on hand, but you can get several blocks for about $5 at Hobby Lobby. Paint I had as well and varies depending on where you get it.