1. Cut an arch across the top of the plywood with a jigsaw. Smooth any rough edges with sandpaper.
2. For the bedposts, use the table saw to cut the 4x4s to the desired height, and top them with finials; use wood glue to secure them. On one long side of each 4x4, nail or screw a 1x2 the same length as the short sides of the plywood.
3. With the plywood facedown on a flat surface, set the posts on either side with the 1x2s overlapping the back of the plywood. Screw through the 1x2s into the headboard to secure.
4. Prime the piece; let dry. Then paint the piece; let dry.
5. Lay the quilt, right side down, on a flat surface. Trim it horizontally to fit the plywood if necessary. Place the headboard on top of it, then wrap the quilt around the arch, stapling to secure it to the back of the plywood.
6. Place the headboard against the wall, and either brace it with the bed or secure it to the wall with long drywall screws.