Many people consider making doors to be the pinnacle of woodworking achievement. What stops most people from attempting it is the simple fact that most door panels are wider than wood is commonly available. The options usually boil down to buying doors or using plywood door panels. However, it is a straightforward process to make your own door panels out of lumber without having to rely on plywood.
Cut the wood to rough length. Use a miter saw equipped with a stop block to make the cutting go faster.
Joint both long edges of the wood on a jointer to ensure they are straight.
Glue the individual boards to form a door panel. Apply glue along the long edges, and spread it with a brush or glue roller. Use clamps spread about every 8 inches to apply even pressure to the panel.
Remove the door panels form the clamps after 24 hours. Use a chisel to scrape off any glue that dried on the face of the panels.
Pass the panels through a drum sander, or use a random orbit or belt sander to sand the panels smooth.
Use a table saw to rip the wood to the finished width. Cut the panel to the desired height.
Use a router table to rout the desired edge style on the door panels. For shaker-style and flat-panel doors, skip this step.