In this Instructable, I used a Post Office door manufactured in 1960 to make a bank.
The project used reclaimed wood for the body of the bank.
You can choose any wood you would like for the project.
Depending on the wood you use, this project can be made for about 25 dollars.
It turned out to be easier than I expected to figure out the combination of the lock and I will describe the method in the Instructable. So, if you see doors that don't have combinations, don't be hesitant to buy them.

Step 1: Tools and Materials

Step 2: Figure Out the Combination of the Door

Locks like this have three tumblers. The order of rotation is:

To determine the combination

Turn the dial counter-clockwise one full rotation
Keep the door verticle
Wait until the cylinder closest to the front of the door has a wedge in it where the lever will move into.
Write that letter down.
Turn the dial clockwise past the letter and continue to turn until the middle cylinder has a wedge lining up where the lever will move. Note the letter (it might be between two letters, so note that)
Turn the dial counter-clockwise until all three cylinders line up. Note the letter or letters.
You should now be able to turn the knob in the front of the door to open the mechanism.
Close the door and turn the dial one full counter-clockwise rotation. If the combination works, then you are finished with this step.

First, cut the sides to the needed width (4 inches in my case)
Second, cut the pieces to the desired length and add 1/2 inch. You want to be able to cut to the exact dimension when you cut this on an angle.
Unplug your saw and tilt the blade to 45-degrees. Measure this with a speed square. Plug the saw back in.
Using either a miter gauge or a table sled, cut the pieces on a 45-degree angle. I think a table sled helps here because it provides more surface to stabilize the piece. Continue to cut closer and closer until you exactly hit your mark. You want to be precise here or the case won't line up.
Do this for all four pieces of the bank body.
Unplug the saw and return the blade to 90-degrees. Measure the angle with a speed square.
Raise the blade 1/8 inch above the table sled.
Mark a line 1/8 inch from the rear of each piece (on the inside).
Starting on that line cut a slot for the masonite. You will need to cut 1 1/2 blade widths for a 1/8 inch slot.

Begin by cutting the masonite to 3 1/2 by 5 1/4 inches. That will fit snugly in the back of the bank.
Put glue into the slots for the masonite and on all 8 mating surfaces (45-degree cuts).
Put them all together and use blue painter's tape to keep the bank body together while the glue sets.
I always glue on top of waxed paper so that it doesn't stick to the surface.
You can also use clamps but it can be frustrating to tension them just right so that it doesn't wedge out a side. I've found that tape provides adequate pressure for this. Once set the glue is stronger than the wood itself. If you want to reinforce the joint you could add splines but that probably isn't necessary.

Drill 1/6 inch pilot holes using the drill.
fasten the door to the sides using a driver. You can see that I used a right-angled driver to make it easier.
Vacuum and use a microfiber cloth to clean out any sawdust.
Use window cleaner to clean the window.
Attach feet on the bottom to avoid scratching your furniture.
Depending on the wood you use, you could at this point use oil or polyurethane or even paint to finish the project. I chose to keep the wood natural because I thought it showed it's character and age.

I hope that you enjoy this build and I welcome your comments and questions and will especially enjoy seeing your versions of this build!