There is a drywall nail in the end of the barrel, and another as the hammer/trigger. The heads were cut off, the nails filed smooth, and the trigger given a touch with the lip balm occasionally. It's about 10-12 years old now, so the wood feels just so. It's a piece of pine what I felled and milled by my ownsome.
The legs of the rubber band and the trigger post make up the sights.
Yes, it is messy, but it is 99% effective. I had to break it out today.
Also works on garden pests.
Hey, tomato hornworms. I'm ready for you...