If you have something very large you would like to frame but find the cost of purchasing a frame prohibitive, check out this how-to for an extra large picture frame!
Raw lumber - I used 1 X 6 spruce
Wood glue or some kind of adhesive for wood
4 joint braces or corner braces
Wood stain or paint
2 eyelet screws
Measure out the size of the frame you want. The map I wanted to frame is 32 inches by 45 inches (80 cm by 115 cm). As I was using 1 X 6, the outside of my frame is about 5 feet long.
Purchase your lumber. Try to get as straight a piece as you can as this will help keep your corners clean. If your pieces are long, many lumber stores will cut them for you into more manageable lengths.
Set your mitre saw to 45 degrees and cut. Measure out your interior length and cut again. Make sure that your angles are both facing opposite directions.
Repeat for all 4 sides.
Apply wood glue or other wood adhesive to the corners. Secure your braces.
Allow the glue to dry and then sand the frame. If you are looking for a rustic look, a light sanding will do. If you wish for a more clean look, you may need to use wood filler and spend some more time sanding.
As I was staining a piece of soft, dry spruce, I applied a wood conditioner before my stain so that the stain had a more consistent look. Let the wood conditioner dry and apply your stain or paint.
When the stain is completely dry, attach your picture. To do this with my map, I simply attached the map to a large piece of cardboard and stapled the cardboard to the frame. The map itself will not be damaged and I can easily remove the cardboard if I want to change the picture.
Measure the frame into thirds and on the top third, attach the eyelet screws. Thread the picture wire between them and secure. I put a bit of masking tape around the ends to prevent scratches.