Open Snapchat
Take a photo or video
Tap the sticker icon on the right side
Select the scissors icon
Trace around the part of the image you want to turn into a sticker
Release to create the sticker
Tap the sticker to save it
Use the sticker in future Snaps by opening the sticker menu
Tap My Stickers to find your custom sticker
Place it on your Snap and send it