This is a simple, fun, quick decoration for Hallowe'en or anything else that needs bats. It's made from an old umbrella, hence the word 'brelly' in the name. All it takes is around 15 minutes and some materials that you may very well have lying around the house. I used:

1 old black umbrella, the collapsible kind, slightly broken. (Full size will work too.)
2 lids from plastic jars in a colour that's at least somewhat translucent, so: not black
Some black tie-wraps, unless you are lucky. I was
Glue
Clear packing tape
A pair of scissors
A pair of pliers for cutting and bending
A permanent marker (black)
A torch or some other light source. I used a head lamp and another camping lamp

Step 1: Getting Into Shape

Here's today's victim: a slightly mangled collapsible umbrella with some dust and a printed brand (yes, it's a giveaway from an event). Perfect for making into a bat.
It's divided into 8 segments, as is common; if your 'brelly of choice is divided into 10 segments instead, you will have to make adjustments.

We start off by picking three segments to represent the head and ears. Pick the ones with the printing we want to get rid off, or the most broken part.

Find the spot where the top of each ear should end up. It's about halfway between the middle and the edge of the 'brelly. If the fabric is sewn to the ribs in that spot, then you're lucky and should leave the stitching intact; if not, we will replace it by a tie-wrap.

Cut away almost all of the fabric in the first segment, but leave a little triangle that goes from the shoulder to the tip of the ear, and represents the side of the head.

The second segment contains most of the head. Cut diagonally down from the tip of the ear, then horizontally to form the top of the head, then up again towards the tip of the other ear.

Third segment is the mirror image of the first. Check the pics and you'll figure it out.

Now cut off the part of the ribs that extents past the ears. If the fabric is not fastened to the ribs, use two tie-wraps (or some string) to fasten it in place.

On the other side of the umbrella, cut the shape of a tail and two paws out of the fabric of one segment. Leave the ribs intact.

Now we have a bat-like shape!

Step 2: Making Eyes

For the eyes, find (or make) something round and translucent. Plastic lids come to mind. Any colour is good, especially if you have two of the same. White is fine too and has the advantage that you can use colourchanging LEDs behind it and the colours will show up very nicely!

I used these blue lids because they were there.

Cut out the rough shape of the eyes; cut a little smaller than the eyes are, and make the shape straight on top, slanted towards the middle so it looks menacing. Think of the shape of Spiderman's eyes. Slide the lids in to see if they fit well.

Use a black marker to draw a pupil. I made it narrow and cat-like and drew some lines around it.

Use a suitable glue to stick the eyes to the fabric. Reinforce the construction with some transparent tape on the back. This also helps fasten the eyes to the ribs.

Your bat should now look rightly annoyed.

Step 3: Finishing Up

We don't need the stem anymore! Cut it off. Secure the mechanism with tape to make sure the umbrella will not fold in; it shouldn't do that anymore. It's now a bat and destined to be folded out forever.

Curl up the former stem into a hook for easy hanging.

Now add some backlighting! I hung my BrellyBat from a ceiling lamp to demonstrate; it makes a nice lampshade too, if you're into that kind of decor.

For use as a decoration, use any kind of torch, camping light, whatever you have at hand to light up the eyes from the back. Avoid real candles as the fabric will burn easily.

Step 4: Showtime!

Hang up your BrellyBat where it will be seen! It makes a great door decoration for Hallowe'en. But it's fine for other spooky festivities and general fun too.

In the pictures above, it's strung up by the ends of its wings, using rubber bands to keep it taut. It flaps a bit in the wind, which adds to the effect. I've taped up some camping lights to make the eyes light up.

Go batty, and have fun!