1. A regular paint roller is the appropriate alternative to brayer. They are available in a variety of ‘naps’. You can use either foam rollers or the more common cloth rollers. You should use a very tight nap roller.
2. Now start keeping your pictures on the object. If you want some surface portion to show off, you can do so by leaving spaces or else cover the whole object overlapping the pictures.
3. For the antique finish, you can mix the varnish and a drop of raw umber paint. Now coat the object with the gloss varnish and let it dry.
4. To be perfect enough you can sand your images from some areas. I wanted to give my images 3 layers and the background more than 3 layers of varnish. Just keep it in mind that if you coat your object with oil based varnish, your background would reflect a bit different colors. Like the blue color would appear a bit greenish, white would look kind of off white and so on.
5. After sanding your picture, you may paint a few portions of your image. You can either use a paintbrush for that or china graph pencils. For minute colouring use 00 paint brushes. Note that the china graph pencils blend very nicely...