Introduction: Hidden in Plain Sight - CAN You See It?

Warning: 5, 15 or 50 - ADULT supervision highly recommended
¡¡¡ Sharp edges and hot surfaces are inherent hazards of this project !!!

Imagine a completely secret hiding place only you and the cook know about! The US Seal Teams and Special Forces call it a cache - a fancy French word for "hide" or "hiding place." For eons people have been using caches for food & supplies when traveling to / from locations, to store food for long winters or to exchange "Top Secret" jet fighter plans while conducting spy missions. Did you know there is a river in Colorado named "Cache la Poudre?" - That is French for "The (gun) Powder Hide" from the old trapping days. The thrill and intrigue of making and utilizing your own cache can be experienced today!

When considering what to use and just how to make your own "hide" start with your environment. You will want to design it in ways that fit your lifestyle and living situation, and details matter. For example, what are you wanting to hide? The size constraints of your 'treasures' directly dictate the size of cache required. You can (pun?) put small items in a big cache, but if you only want to hide currency or jewelry, a smaller cache is easier to manage (and it is best not to put all your eggs in one basket i.e., don't hide ALL of your cash in one cache).

A cache is essentially camouflage for something valuable. It is easy to find examples of camouflage all through nature. Species of snakes, lizards, birds, fish, big cats, spiders, bugs - predators and prey around the world - use camouflage to either lure prey in (or get close enough to it) to eat it; or to hide from predators to keep from being eaten! Going with Nature’s model of camouflage (to "blend in" or be "hidden in plain sight") I decided to use materials (a large can of refried beans) which actually come from my supplies and replace the new cache in its customary location: the cupboard or pantry.

For your cache consider where it appears 'natural' - Would a jar of instant coffee look 'natural' next to a coffee pot? No. How about a large hard-back book on a shelf of paper-backs? Your cache should belong to its environment. Next, is your cache portable? If the SHTF and things get bad in your neighborhood, would you be able to quickly gather and transport your cache? After all, the items in your cache are valuable or you would not cache them! Traveling with canned food items (maybe some tortillas to go with the beans?) in a catastrophic situation is A LOT less conspicuous than traveling with a small safe or books or other non-essential survival items. Think about it. Having a few food items with your emergency blankets & jumper-cables in your trunk in case of a vehicle break-down in bad weather isn't suspicious! And why the choice of the cupboard or pantry for a cache at home? When was the last time you saw a “crime scene” on TV with the pantry ransacked or the canned goods closely examined? Nobody in their right mind would hide thousands of dollars in a pantry or in a trunk! The cupboard / pantry are not obvious hiding locations, are readily accessible any time day or night and have other things I need in a "Bug-Out" scenario.

In addition to location / environment are other physical characteristics such as weight and appearance ('Best By' or expiration date & the Paper Label) to take into account. In this project we will address the weight and label preservation specifically. As to the 'Best By' date - there is always the hazard of a well meaning person removing 'expired' canned goods from your kitchen. Best to keep dates current! This is addressed at the end of the project. Weight is addressed simply because it would be pretty obvious if your cache (a can of beans) weighed radically different from another can of beans on the same shelf. The reasons for maintaining the appearance (label integrity) is obvious - it should appear like it just came from the factory.

Last, it would be kinda silly to build a cache that needs to be hidden somewhere . . . you follow me? The cache itself is (or should be) the concealment for the 'secret compartment'. Where would you expect to find a can of refried beans? On a cupboard shelf? Or in a box in the trunk? Definite possibilities. How about under a drawer in the desk? Or on the shelf in your bedroom closet? Which brings me to the final consideration for this project. Your cache should be located somewhere easily accessible without being overly obvious about it. I think you get the idea. Put some thought, consideration and time into your cache. Robbers and thieves and foreign spies certainly will devote thought and spend time trying to find your secret treasures.

So, my rationale for the beans, refried? Aside from the above mentioned:
1. I eat beans
2. I have beans on the shelf
3. I eat beans when camping & traveling (they look 'natural' with tortillas or tents - don't forget a can-opener!)
4. Refried beans are dense (an easy characteristic to replicate)
-- Ever tried shaking a can of refried beans? Virtually solid. Part of the camouflage.*

* canned vegetables or fruit or meat WILL work. Keep reading closely as the processes are IDENTICAL, except for the balloon . . .

Author's Note: Read each step completely before diving into it. Actually it probably would not hurt to read the whole project first, consider the process and think about ways you can make the idea(s) work for you in the simplest fashion. Don't forget to look for POST PRODUCTION TIPS to save yourself some time on certain steps.

Like Secret Codes, 'Enigma' Machines & 3D (multiplayer) logic puzzles?
All in 1:


1 Can Refried Beans – 31 oz – 1 lb. 15 oz
** Smaller fruit or vegetable cans will work with a small modification to the process Sorry, ‘pop-top’ cans will not work (no 'lip' on the bottom).

1 Plastic spice jar or Medication container or similar
– any Plastic container w/ a THREADED cap that fits inside your can
Any STRONG glue – I recommend Go2 Glue -
1/2 lb (approx) Canning Wax (Parafin) - unscented candles will work in a pinch -
apprx 2 lbs pea-gravel (washed) - local 'old-school' play ground or dirt road

Equipment (required):
Small sharp pointy device and/or small drill bit (I used an Xacto knife) -
Standard (manual – geared) can opener (see photo) -

NOT Pictured (required):
patience - for everything to set completely you MUST allow time
file or sandpaper
tooth pick or similar
apprx 12" flexible wire – cut in half
Needle-Nose Pliers (stiff wire)
old small pot (double boiler if you have it)
Hotplate / Stove
Aluminum foil
- 2 pc - 3"x6" (skirt)
- 1 pc 6"x6" (folded to fit as temporary cap)

2 (or more) rare-earth (neodymium) magnets -
Hairdryer -
Cotton balls - to keep things from rattling around in secret compartment
1 or 2 lrg balloons (2-3" in diameter)**

Cache - what we are making with the can
Can - the can
Cap - the threaded plastic lid to your secret compartment
Compartment, Secret - the threaded plastic bottle that goes inside the cache
Lid - the end of the can / cache, metal

** If you only have a can of vegetables or fruit, keep reading. You will need a balloon - or other handy durable 'rubber' (pun?) water-proof device similar to a balloon. ;)

Step 1: Prepping the Cache 1: ‘Secret Compartment’ Cap

1. Plastic Cap
a. cut / drill holes in the lid – 6 or 8 evenly spaced near the perimeter of the cap - see photo
b. keep the center whole. No pun intended. You will be pressing this plastic cap to the metal can lid with your fingers (and/or magnet) and this glue is pretty crazy being water proof and flexible. Its kinda hard to get off fingers or clothing or work areas
c. make the holes just large enough to slide the tooth pick into
d. trim off any excess plastic from the Top of the cap
e. the holes in the cap help hold the lid (the end of the can) tightly (flat) to the body of your cache (the can).
-- Soon glue will be applied in each hole to insure there is glue both under and in each one making a stronger bond

2. Set aside for later

Step 2: Prepping the Cache 2: ‘Secret Compartment’ Body

1. remove the safety tab - IMPORTANT - see photos
a. this is necessary to get the cap off later
b. pull & twist (needle-nose) or cut (Xacto) out the tab which locks the cap in place.
c. test the cap on the container - it should tighten firmly and unscrew easily = NO TAB

2. at the very BOTTOM of the container (at the bottom edge - see photos) use the smallest sharp pointy device at hand and carefully drill / poke 4 very very small holes across from each other around the perimeter
a. photo shows wire passing through 2 holes in proper location

3. set aside - we will do the wire in a few steps

POST PRODUCTION TIP: Two holes across from each other & one wire would be as effective as four holes in most cases

Step 3: Prepping the Cache 3: the Cache Camouflage Aka the Refried Bean Can

1. Opening the can - SHARP EDGES AHEAD
a. wash and dry your hands. Dry. (and / or use gloves)

NOTE: Remember, this is the ‘Camouflage’ for your secret compartment . You want the label to look like it came from the store – clean - without a lot of unusual marks or wet or waxy or “gluey” or bloody finger prints

2. weigh the can (if possible) and write down weight (this is your target weight)
a. if you have another identical can you can weigh it instead
-- curiously two different cans will almost always weigh a bit different so we are shooting for a ball-park figure

3. with the can UPSIDE down, gently push / slide the label as far as possible towards the TOP of the can
a. setting the can on a table top (upside down) helps get pressure on the can to get the label to slide UP to the TOP of the can
b. see photo, the label will slide up towards the top
c. this is to keep the label out of the path of the can-opener

4. using the can opener (see photo) remove the BOTTOM of the can

NOTE: The rim of the can will be ON the lid, not on the body of the can.
¿ Did you know that you can use a manual can opener in TWO different ways ? Now that is value!
a. the can-opener should be 'parallel' to the lid
b. try to keep the cutting edge of the can opener as close to the rim as possible

NOTE: As soon as the lid comes off the body of the can, the rim of the can is ¡SHARP!

5. empty the can of its contents

6. wash can - DO NOT get the label wet - this means DRY hands & fingers
a. ever try to wash a dish and NOT get your fingers & hands wet ?
NOTE: – Washing the can is the tricky part in the process when it comes to getting cut
b. put a few drops of soap and about 1 inch of hot water in the can
-- don't touch the label with wet fingers
c. using a brush with a long handle wash the inside of the can
NOTE: – that edge is ¡sharp!
d. rinse the inside of the can . . . being water conscious about the label
e. set can with the opening down (or right-side up) on a towel to dry

7. wash the metal lid of your cache
a. the lid may have some sharp edges. It shouldn’t but use ¡caution!
b. the lid may have an expiration date – don’t wash it off if you can help it
c. note the dimples made by the can-opener (photo) - that is why everything is upside down

8. file or sand the inside edge of the lid
a. at minimum you need it smooth
-- a small angle wouldn’t hurt, but a belt-sander is almost needed for that
b. take your time, you need this part for the next step

9. let things dry

POST PRODUCTION TIP: Use some painter's tape (blue or green masking tape) to protect the side and label of the can. Actually, it wouldn't hurt to cover the entire can body until the cache is complete.
Would not hurt to have a band-aid handy - unless it is merely a flesh wound :)

Step 4: Assembling Components 1 - Cache Lid

1. Top / lid of the cache (bottom of the can)
a. (optional) place one magnet in the center of the exterior side of the metal lid
b. place the lid of the can right-side down (magnet down)
c. put a drop or two of glue in the approximate center of the cache lid

2. Plastic cap
a. put a drop of glue in each hole inside the plastic cap
b. using toothpick work the glue through the holes so that the glue is on the top of the plastic cap
-– top and bottom of each hole

3. place the plastic cap top-down (threads up) on the spot of glue on the lid
a. you can put another small drop of glue in each hole to make a better connection

4. (optional) put another magnet in the center of the plastic cap and center as best you can
a. the glue stays fluid for a bit
b. it doesn’t need to be EXACT
c. as long as everything is lined up when ASSEMBLED, the exact center of the lid inconsequential

5. set aside to dry for 24 hours - seriously - you want this bond as strong as possible
a. take your time for the following steps - you have 24 hours to get every step prepped, practiced and ready to set in place

Step 5: Assembling Components 2 - Cache Body (the Can With Sharp Edges)

NOTE: be aware of paper label integrity and try to avoid damage

1. using sand paper (or file) sand / file down the sharp edge of the can
a. take your time – the glue on the cap & lid takes a loong time to set

2. try to ‘knock down’ any high or rough points in the edge (see photo)
a. you want a flat edge

3. with some elbow grease and patience you can carefully make the can edge safe.

NOTE: This is the ‘business end’ of your cache. Every time you access your cache, this edge will be PROMINENT in the operation and will easily cut fingers.

4. make this edge safe

5. take your time, minding the label
a. see photo - the label is scratched - try to avoid this

Step 6: Assembling Components 3 - Secret Compartment

1. Anchor for secret compartment
a. press one 6” length of wire through one hole and out the other and ‘center’ it
b. repeat with other wire
-- they should cross in the middle, but not required

2. using pliers (or fingers) wind & bend the wires in any configuration that suits you
a. see the several examples in the photos
b. with 4 wire ‘legs’ you can use the wire to anchor and help center the container in the can
c. notice the photos, the anchor wire is bent so as to keep the wire below the rim of the compartment

3. place the ‘wired’ container into the can for a test fit
a. photo only has one wire, but you get the point
b. your secret container is shorter than your cache, so approximate how far down you bend your wires to keep the secret compartment above the bottom

4. we are placing gravel in the can first (and wax), so make your ‘legs’ slim / open / simple enough to work down through gravel and travel back up the sides of the can (not so high as to be above the level of the gravel or wax)

5. balloon Users - keep your legs short to none
a. do not put any sharp angles in your legs
b. a punctured balloon could lead to future leakage

POST PRODUCTION NOTE: Keep the holes small. Some wax will leak into the bottom, but not much. You could try gluing the wire where it exits the container, but it seems more trouble than it is worth.

Step 7: Assembling Components 4 - Making Your Cache 'Real'

1. approximating weight
a. fill the can about half full of pea-gravel
b. put the can, 2 bars of wax (½ lb), the glued lid and secret container on the scale

2. remove (or add) pea gravel until the weight is approximately the same as an unopened can
a. set this amount of gravel aside - you will be using almost all of it
b. if you haven't washed the gravel yet, do so now drying

Step 8: Assembling Components 5 - Estimation

NOTE: if you are using a balloon, skip to step 3
1. get the approximate measurement of the gravel that will be under your plastic container
-- too much gravel will make it difficult to work the wire to the bottom of the cache
a. measure the interior height of the cache using a strip of paper and cut to length
b. carefully (the glue isn’t set yet) screw the secret container into the cap on the lid of the cache
c. using the same length of paper from "a" measure the height of the plastic container screwed onto the lid
d. from this mark to the short end of the paper is the approximate depth needed for the pea gravel under the container (labeled 'fill' in photo)

NOTE: This is also the approximate height of the 'legs' for the anchor

2. proceed to the next step after the glue is fully cured
a. make sure it is cured (wait the whole 24 hrs) before going to the next step

Balloon Users:
3. prepping the balloon
a. fill the balloon with just enough water & air for it to make a sloshing sound similar to a real can of vegetables / fruit
-- two table-spoons of water with about the same volume of air should work - there is not A LOT of air in a can to start with - don't over do it
NOTE: the air in the balloon is crucial to the sloshing sound - without air in the balloon, the wax will fill all the space trapping the water = NO sloshing sound
b. consider that the balloon (air & water) contraption needs to fit easily under your secret compartment 'legs' & body
1) you don't want the balloon pressing up as it may effect alignment later
c. skip any gravel for this 'layer'

POST PRODUCTION TIP: Other than approximating the length of the legs this step is largely unnecessary.
-- Put enough gravel in the bottom of the can to give the legs something to 'set' in - kinda like how concrete works. About 1/4" would work well.
-- I found with 'a lot' of gravel in the top of the cache it seems a bit top-heavy.
-- This 'short-cut' (using less gravel at the top) uses more wax.
-- Part of the reason I did this step in the first place was to use less wax by using rocks as filler. Lessons learned.

Step 9: Assembling Components 6 - Test Fit

1. Get a feel for the assembly process
a. practice placing your secret container (with legs) firmly into the pea-gravel (gente on the balloon) to get a feel for the process
b. place the cache lid on the can to get a feel for how it will line up
1) if you look closely you can see where the lid was originally – shoot for that spot
2) sand / file lid and can again to insure a close fit before final assembly with hot wax
3) get a clear picture where the lid fits best on the can

c. tighten the secret container to the plastic cap (glued to the cache lid) finger tight – snug
1) practice pressing / turning the assembled lid / secret container into the gravel
2) adjust how tight the cap needs to be on the container to get things set properly
3) keep the cap tight on the secret compartment or the cache lid will be loose
4) pay attention to how things line up when fitted and put it together in the same way in the next step

2. practice setting everything in place in the gravel (on the balloon) a couple times (lid properly aligned with can, cap tight enough on secret container, etc)

3. BALLOON users - make sure your 'legs' don't puncture the balloon
a. experiment how much water / air you need to fit under the compartment and still 'slosh'
b. adjust how tight the cap needs to be on the container to get things set properly
c. pay attention to how things line up when fitted and put it together in the same way in the next step

NOTE: You want the legs to 'rest' against the balloon - not 'press'!

Step 10: Assembling Components 7 - Anchor Secret Compartment

1. first 'anchor' layer
a. melt 1 bar (.25 lb) parafin (wax) in old pot
b. immediately pour the hot wax over the gravel (or balloon) in the can
c. place the assembled, 'wired' secret container (attached to the cache lid) into the wax and gravel (or balloon)
d. line things up like you practiced in the previous step

NOTE: If there are any ‘errors’ or small places that just don’t fit ‘right’ don't worry too much, simply turn that side to the back in the pantry.

2. take your time lining things up
a. if you have magnets you can use them to help hold things in line(see photo)

3. place smaller can (or two) on the lid of your assembled cache to hold things tight until the wax fully hardens

4. wait until everything is well cooled

5. remove the lid from the cache (hopefully its still glued to the cap!)

6. it is likely some wax may have enter the plastic container – no worries, its not much if you had small holes

7. if things go wrong (isn't lined up properly, etc) no worries! Simply use the hair-dryer to melt the wax and reposition things

Step 11: Assembling Components 8 - Final Details

1. filling the cache
a. add pea gravel inside the cache (along the sides of the secret compartment) to the top of the inner chamber
b. weigh the cache (completely assembled) with the loose pea gravel and 1 .25 lb wax bar
c. adjust amount of gravel to approximate the correct weight

NOTE: I came up with the idea for the aluminum cap and skirt after I completed my model. That is why there is hardened wax covering the gravel already.

2. using the aluminum foil (6" x 6") fold a temporary cover for your secret compartment

3. using the strips of foil make a 'skirt' for the body of the cache
a. fold the long edge of a large piece of foil over to 1/4" - 1/2"
b. hang the small edge of the foil over the edge of the can, circling it
c. repeat the process with the second piece of foil hanging the small fold over the lip of the can

4. melt the 2nd bar of wax and carefully pour it over the pea gravel to the desired depth

5. wait for wax to fully set

6. again, if you have any problems, melt the wax with a hairdryer and try again

POST PRODUCTION TIP: Rather than do this step all at one time, using layers of gravel covered with wax covered with gravel covered with wax would make it easier to hit the target weight.

Step 12: Assembling Components - Options – Vegetable & Fruit Cans – Any Size!

1. to replicate the sound of the juice in items like corn or fruit:
a. fill a balloon with a little water (2 Tsps)
b. blow a bit of air into the balloon and tie
c. rather than pea-gravel, place the balloon in the ‘bottom’ of your cache
d. add enough wax to cover the balloon and hold secret compartment in place
e. after wax sets add pea gravel for weight and finish as above

2. you could use electric tape as your anchor rather than wire

Step 13: Using Your Cache

Which of the three cans is the cache? Want a clue? It is not the top one.

Place your treasures (usb sticks, sd cards, cash, jewelry, love letters, etc) inside the secret compartment, pack in some cotton and put the can back on the shelf. Behind other cans and / or in a stack. Hidden in Plain Sight!

Best by date:
As the years go by it will be necessary to transfer the secret compartment to a newer can.
To accomplish this:
1. heat up the sides of the old cache to melt the wax enough to remove the interior (gravel, wax and secret container attached to the lid)
2. empty a similar sized can of its contents
3. place the wax / gravel / secret container 'glob' into the new can and seal it in with more wax making absolutely sure you line up the 'old' lid with the flat lip on the new can

Step 14: FREEBIE! Interested in How Professional Soldiers Make & Use Caches?

The pdf can also be downloaded here:

Step 15: Things I Would Do Differently?

1. Less gravel. I would not use as much gravel in the 'bottom' of the cache - fewer rocks and more wax
-- this model weighed in a little heavy, but close enough

2. More time on the metal lid and can edge
-- would have fit a little better.

3. Rubber gloves. Several pair.

4. Use a glass jar
-- would increase weight and volume of the compartment
-- would require a rotary tool to anchor the jar

*Light bulb photo courtesy of a web-site with copyright free images

Step 16: Thank You for Reading My First Instructable!

I hope you find the information useful! And please vote for your favorite ideas!

Secret Compartment Challenge

Participated in the
Secret Compartment Challenge