Come game time, just post an image to the game channel. Easy!
See Slack’s documentation for adding files.
Mediums
You can draw with whatever medium you like. Digital. Pencil on paper. Pen on a post-it. Sharpie on an old envelope. Finger on a dirty car windshield. Just take a photo with your phone and post to Slack.
3-Minute Animal comes with a built-in Sketchpad that posts to the game channel with just one click. Or, use your favourite image editor program.
Drawing Tools
Here’s a few browser-based drawing tools:
And here’s some free drawing tools you can install to your workstation:
Supported Image Formats
Slack supports png, jpg, jpeg, and gif image file types in posted messages1.