I dreamed up this hiding contraption / device specifically for this instructable and specifically for the "secret compartment and doors" contest, so please vote for me if you enjoy my Instructable . It is designed with multiple levels of protection in mind. Firstly, it will be extremely hard to find the area of the hiding spot. Secondly, it will be very difficult to access the hidden goods without knowledge of the device. Thirdly, even if the hiding place is discovered and someone is determined enough to get it out it will take time and a great deal of effort.
The basic idea is to have an underground storage container that can only be opened by a hidden mechanism. Being outside will make it difficult all by itself but being hidden underground in a "pipe" will make it that much more difficult. Plus, did I mention there is a TRAP DOOR involved? This sounds awesome! Next, we will gather the materials we need.
Step 1: Bill of Materials
Few feet of 1.5" PVC PIPE cut into lengths (length determined by hole depth)
Few feet of 1" or smaller PVC PIPE. (length determined by hole depth)
1.5" PVC end cap (OPTIONAL)
1" 90 elbow (OPTIONAL)
2 strong magnets
retractable key ring (I got mine at the dollar store)
large paper clip
small square of PCB (or alternately use a sturdy and thin piece of cardboard)
Step 2: Find the Hiding Spot
Step 3: Dig a Hole and Measure It.
Unfortunately, it turned out to be extremely difficult to dig deeper than about a foot. So, I resorted to digging the old fashioned way. With a stick and my hands. UGH!
Do not dig a hole in this manner. Please use real tools, don't be like me. My hands were killing me for days after this.
In short, dig a narrow deep hole. When you decide to give up, this will be your final depth. The main problem with digging below about a foot is the sediment and rock that is down there, using a gardening claw can really help get the rocks out.
Next, measure the depth of the hole you just dug. Measure and cut the PVC pipe to that length minus about 2 inches. Also the diameter of the hole should be around 6 to 10 inches. This is because our pipe will have some exterior structure for the "trap door" mechanism.
NOTE: this is the most difficult part of the entire build. Once you get past this, the rest is a piece of brownie batter cake!
Step 4: Assemble the Monstrosity
So, what we need to do is, about half way down the pipe, cut a slit (see images above). Make sure you don't cut all the way through the pipe. I used a coping saw, you will use whatever you have on hand, and YOU WILL BE VERY CAREFUL.
Next, cut a small piece of cardboard or as in my case PCB to be used as the trap door. Drill a small hole near the edge of your trap door. Now is a good time to seal the bottom of the main PVC pipe, I used a piece of cardboard and copious amounts of tape. This should keep all the dirt out of the lower end of the pipe, if you are really ambitious you can get an actual PVC cap that fits the pipe when you go purchase your pipe. If you decide to use a PVC cap it would be best to also use the PVC cement you have to seal that cap on, making a water tight seal. See the images for the way I did it.
The hole in the "trap door" will be used as the pivot point to allow the card to swing out of the way when necessary. A straightened paper clip or some steel wire can be threaded through the trap door hole and taped to the pipe to create the pivot point. (see image)
Next attach the retracting key ring to the opposite side of the trap door. I did this by putting another small hole in the trap door (opposite side of the pivot point) and attaching the key ring to it with a small piece of steel wire. In this way the retracting action will keep the trap door normally shut, and will allow it to re-shut.
Once the retracting mechanism is in place and the "trap door" is in place and secured at it's pivot point it is time to trim the excess trap door material so it won't get caught during the opening/closing. Trim anything that sticks out from the outside of the pipe, when the trap door is in place. (Meaning when the trap door is closed and nothing can get through the pipe.)
Next, we need the mechanism to pull open the trap door. It basically consists of a string that pulls the the trap door open, and when the string is released the trap door closes.
I added a 6" piece of the 1.5" PVC pipe to the main pipe to be used as a spacer. Then, I attached the smaller 1" PVC pipe to the spacer pipe (see images). The pull string will run through the 1" pipe and must have a ring terminal or similarly large item attached at the end to keep it from falling into the 1" diameter pipe. At the bottom of my 1" pipe, where the force is applied to the trap door, I added a 90 degree elbow, to ease tension on the string and make it easier to pull (optional).
The spacer pipe is necessary, as it gives the trap door room to open, otherwise the small diameter pipe wouldn't have the clearance to open the door fully.
When putting the pipes together I held them temporarily with tape, then when i was happy with how each item went together I used the PVC cement to hold them permanently, and then removed the tape. PVC cement is easy to work with, just read the directions on your bottle and use with plenty of ventilation. I allowed mine to sit and dry for about 2 hours and it was a strong bond by that point.
Now it should be assembled enough so when trap door string is pulled it will open the trap door and when it is released the trap door will re-shut. Be sure that when the trap door is fully opened the PVC pipe is completely unobstructed. And when the trap door closes again the pipe should be fully closed off.
Next, we want to cover the outside of the structure with tape and or thin cardboard. This should allow the trap door mechanism and pull string to move unobstructed from dirt and roots that may surround the pipes.
After covering the outside of the monstrosity in cardboard and tape, be sure to check the trap door again to make sure it can fully open and fully close without any problems.
You are now finished assembling the monstrosity, and because it is so ugly there is only one thing we can do. Bury it!
Step 5: Bury the Monstrosity
We need to fully bury the middle section of PVC, it should be shorter than the other 2 pieces anyway. The main PVC pipe should come right to the surface or possibly 1/4 inch below the surface. The smaller diameter PVC pipe should be just below the surface, with the pull string "ring" not visible but easily accessible from the surface.
In use, both the main pipe and the smaller pipe should have bags stuffed in them to keep dirt out. Then cover the 2 pipes with small scraps cardboard and cover that cardboard with dirt from the area.
Step 6: HIDE YOUR STASH
In order to hide your stash, first, put the stash in a zip-lock bag or similar water resistant bag. Then wrap the bag with string and tie it off. At the free end of the string, attach one of the magnets. Push this whole thing down into the main pipe, then open the trap door and allow it / force it down to the bottom. Then put your plugs into your pipes and cover with cardboard and dirt or leaves.
When you are ready to retrieve the stash simply use a magnet attached to a string. Lower the magnet down into the main pipe, then open the trap door, and hold it open. When the 2 magnets meet-- pull up the string. Then, pull the string with the bag attached and pull out your stash.
Step 7: BONUS HIDING PLACES
A nearly full paint can. Make sure that if the can is shaken the item is soft enough to not bang. It won't ever be found if you don't want it to.
A semi-permanent hiding place is to put the item to be hidden in a decorative concrete block.
It's simple, mix up some concrete. This stuff is ridiculously cheap and easy to use.
Put the item in the mold, (I used a sand castle bucket.) then pour in the mix and allow to harden.
Then you can hide it in plain sight. Forever. Or for as long as necessary.
Then you can break it open with a sledge hammer and get out your goods.
Thanks for looking and please vote for me in the "Secret compartment and doors" contest if you enjoyed it.