We used to make our own decals as kids. back in the 60's.
We would find the image that we wanted in a "glossy" magazine, Then paint over the image with a coat of "Humbrol" clear gloss varnish. When dry we would apply a second, third and then forth coat. The image was then cut out and soaked in warm water. After a while the paper could be rubbed off of the film of varnish leaving the image on the varnish. A coat of the varnish was then applied to the model, and while this coat was still wet, our home made decal was laid in position.
We would find the image that we wanted in a "glossy" magazine, Then paint over the image with a coat of "Humbrol" clear gloss varnish. When dry we would apply a second, third and then forth coat. The image was then cut out and soaked in warm water. After a while the paper could be rubbed off of the film of varnish leaving the image on the varnish. A coat of the varnish was then applied to the model, and while this coat was still wet, our home made decal was laid in position.