Templates by Email Monster - Hundreds of free, responsive email templates. Pick and edit.
Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
MJML - The open source framework for responsive emails
Autodesk SketchBook - SketchBook drawing and painting software provides designers, architects, and concept artists the tools to sketch ideas quickly and create beautiful illustrations.
Stripo - Stripo is an all-in-one email design platform. We enable our clients to build emails of any complexity, including interactive AMP emails, really fast and easy.
Clip Studio Paint - The artist's software for drawing and painting.