Alex has a ceiling fan. It's a typical ceiling fan, which is fine, but not very Batcave-like. So we decided to replace the blades with something a little more bat-themed, like what this guy made.
I got the recommended quarter-inch birch plywood and cut it into strips, then traced a fan blade onto one of them to get a general shape and size. The various curves defining the not-conventional-fan-blade bits of the fan blade were traced out using a dinner plate.
Once I had the basic design down, I stacked up the birch plywood strips, clamped them together, and started cutting with the remarkably versatile jig saw. I had to move the clamps around a few times to get access to all the places I needed to cut while keeping the stack together. After that, I drilled the screw holes, and painted.
The toughest part of this was installation. Because of the ten-foot ceilings, I was on top of a ladder trying to avoid rattling glassy fixtures to get the dusty old blades off and the new blades on. But it's worth it.