One of my favourite things to doodle is random stickers. I made a fair few Nelf Bear stickers back in the day, even made them in every shade of bear there was. Packed them into a couple of Telegram packs then accidentally lost access when my original account got nuked.
I also stuffed them all into an imgur album, so that anyone can pick and choose and make their own stickerpacks if they want.

After I stopped playing WoW I however have not made any more, instead I occasionally ask people to lend me their 'sonas to practice on.

Other than that I sometimes make little animations, random doodles or even 3D models that I like to release into the wild for people to have fun with. This will be their 'central showcase' hub as well.