When you block mount a poster to wood, the poster -- not the frame -- becomes the main focus of the wall hanging. Block mounting can be accomplished with a few basic, inexpensive supplies and a small time commitment.
Cut a block of wood to the exact height and width of your poster. The wood block can be any depth. Most stores sell sheets about an inch thick.
Mark a spot at the center of the back side of the block, toward the top -- about 2 inches from the top edge for a standard-sized poster -- if you intend to hand the poster on the wall. Drill at that spot, about halfway through the depth of the wood block.
Sand the cut edges of the wood block to smooth. Wipe down all surfaces with a clean cloth to remove the sawdust.
Apply two coats of acrylic paint to the sides of the wood block. Allow the paint to dry to the touch between coats -- a couple of hours. Select any color of paint you desire for this finish. Use the sandpaper to remove any unwanted drips of paint from the wood block. Wipe down the block with the clean cloth before doing this to remove any last bits of dust.
Apply a layer of the glue adhesive to the front of the wood block. Choose from a variety of adhesives for this job -- spray adhesive, decoupage glue, even polyurethane glaze. A disposable paint brush is helpful for "painting" the non-spray adhesives onto the wood surface.
Position the poster over the wood block surface. Lay it flat on the wood with the edges lining up.
Use the roller or a clean sponge to smooth down the poster onto the glue adhesive. Move outwards from the center of the poster towards the edges to reduce bubbles and wrinkling in the poster. Allow the glue to dry overnight before hanging your poster.