Step 1: Gather your materials. Papier mache tissue box form (from Michaels or elsewhere); pretty, fairly thick decorative paper; tape measure/ruler; scissors; Mod Podge (not pictured) or other craft glue; foam paint brush (not pictured); paper plate or other surface to hold glue (not pictured); paper and pen to jot down measurements.
Step 2: Measure each side of the tissue box form - in this case, the top was slightly smaller than the sides and the sides were equal. Add 1/4" to each edge of the top section dimensions. This gives you the measurement for the piece of paper needed to cover the top. For the sides, multiply the width of one side by 4 and add 1/2" (for a little overlap when gluing). Then add 1/4" to the height measurement. This gives you the total length and width of the piece of paper needed to cover the sides.
Step 3: Measure and cut two pieces of paper: one for the top piece (dimensions plus an extra 1/4" on each side) and one for the sides (length should equal the total perimeter (width of one side x 4) plus 1/2" and height should equal the height of one side plus 1/4").
Step 4: Apply an even layer of glue to the top of the box and place the cut piece of paper for the top over the glue, allowing about 1/4" overhang on each side. Carefully glue down the overhang, folding down the corners evenly. The oval opening for the tissues will be hidden for now.
Step 5: Apply an even layer of glue to one side of the box and place the cut piece of paper for the sides of the box over the glue, positioning your starting edge toward one corner and ensuring the paper comes right up to the top of the box, just above the bottom line of the top piece of paper. There will be about 1/4" overhang along the bottom.
Step 6: Continue applying glue one side at a time, smoothing the paper over each one and ensuring the paper is aligned evenly with the top of the box. Glue the paper to the fourth side, over the starting edge of the paper.
Step 7: Turn the box upside down. Apply an even layer of glue to the inside bottom edge of the box (about 1/4"), then carefully fold the paper over the edge and press down the corners, applying glue as necessary to tuck them in.
Step 8: The exterior of the box is now entirely covered. Using scissors or a craft knife, cut into the paper over the oval opening, using your hands to guide you. Do not cut flush with the opening; cut a smaller hole to start.
Step 9: Apply an even layer of glue to the inside of the box, just around the perimeter of the oval opening. Very carefully fold in the paper covering the opening until it is flush with the perimeter. You may need to cut slats perpendicular to the edges of the opening to be able to maneuver the paper better.