I had fun turning an ordinary baseball bat into Harley Quinn's bat, as seen in the Suicide Squad movie! I'll just go through the process quickly, and hopefully the picture serves well as a visual guide. It's a super simple prop to make IMO and you'll definitely enjoy it. I almost imagined myself as Harley scribbling my thoughts on my bat LOL.
I started with cleaning the bat to make sure there are not stains left from the stickers I peeled off (lol) of it, and removed the original bandage on the handle. Then I googled for reference images - find as many as you can showing the bat from various angles!
I did a free-hand sketch of the 'GOOD NIGHT' letters and used it as a template for my bat. Not really sure where I kept that piece of scrap paper but if I find it and also find the time to make a digital copy of it, I'll share it here for free~ Then again, if you wanna be neat, you can choose to type out the words using a computer, have a printed out and just cut out the letters, leaving the center where you can use as a template to colour in on your bat.
Colour it in with red marker! Woohoo! Then outline it with black marker after.
Cursive wordings on the bat...
To be honest, I don't think there is any clear image/movie stills that shows what is really written on the bat that Margot Robbie holds. Most sources seem to point to the lyrics of 'I started a joke' by The Bee Gees, so I went with that. It's very suitable too!
I wrote the lyrics of the song in cursive letters using a pencil on the bat, then went over it with black marker, and going over some of the words in red marker.
The other empty spaces of the bat, you can choose to fill it with suit symbols and Harley's quotes. For symbols, I see most sources have '◆' on them, arranged in fours. As for the quotes, you can use her quotes from either the movie or even better - the comic series!
The band at the bottom, before the handle...
Sketch the outline with a pencil first. I did it free-hand so there isn't any template that I can share. Start with the top and bottom lines so that you can gauge how wide you want the band to be. Then split the circumference into 4 parts and sketch the outline for the diamond shapes in each part. You can also just draw multiple jointed 'X' till you get 4 diamond shapes evenly distributed around the band. Then, draw a smaller diamond shape inside each big diamond.
I coloured the small diamonds with blue marker, left the space between the small and big diamond empty, and coloured the rest of the band with red marker. Finally, I used a black marker to outline the top and bottoms lines.
Cut out a long strip of white fabric and wrap it around the handle area of the bat! You can use brown/black acrylic paint to 'dirty' the fabric a little, to make it seem worn.
A photo from Animangaki 2016 where I wore my Harley Quinn cosplay.