"You could check out Krita, it's a free Photoshop alternative that has damn good animation capabilities. You can load your frames into the app and paint over them in the same way you'd do it in Photoshop."
Gumby Imagined, The Story of Art Clokey and His Creations
The ultimate Gumby retrospective packed with incredible photos and never-before-shared stories. Written by Art Clokey's children, Joan and Joe Clokey, this is the most comprehensive book ever published on Gumby, Davey and Goliath and their creator Art Clokey, a pioneer in stop-motion animation.