Photocopy images onto colored paper, enlarging or reducing as you like; a proportion wheel helps you calculate the percentage, or you can improvise -- a patchwork effect is part of the charm.
The flower image is actually made from six pieces of paper in various shades of blue, not quite aligning.
This cabinet has pull-out shelving. Cut paper to fit your cabinet.
Brush on wallpaper paste with a foam brush. Apply paper, one at a time, and smooth with a wooden roller.