Introduction: Invisible Wall Box Using Optical Trickery


The goal of this ible is to show how to make a wall-mounted box that can't be seen to store / hide things. What inspired me to do this is that I have a small UPS and a few wall-warts hanging around in my stairwell. I will be showing you how to plan out what size box and frame you can use, and how to build that box without the need for frame clamps or corner clamps.

Giveaway: follow my instructables and YouTube channels and post an "I've made it" picture to get the free pro membership voucher I got when this instructables was featured.

Step 1: Figuring Out What Dimensions You Need

The first step is figuring out what size box you need. What will you be storing or putting out of sight? In my case, I want to be able to fit my UPS. The idea of making it as shallow as possible is to make it the least visible possible.

The second aspect of size, is figuring out how high\wide you need the box. You can go two ways for this. The first is to make it flush with the edges of your frame and embrace the fact that it is a raised frame. The second way is to make the box smaller than the frame so that it is not visible from as many angles as possible. The deeper it is, the harder this will be. Also, making it too small will make it harder to hang the frame on it.

Some rules of thumb to help you decide:

  • Most importantly, this is about what look YOU like
  • If it will be in a room where you walk perpendicular to it (alongside the wall on which it is), it will always be visible, go with a box that has walls flush to the frame.
  • If it is at the end of a hallway, or at a wall along which you would not really walk (say end of a rectangular living room, away from all hallways), then we are in business.
    • The smaller the frame, the more difficult this will be
    • On a wide wall, this will be harder to do. Using my diagram, you can determine from what angle the box will be visible using the ratio of the room dimensions.
    • The walls of the box will become visible at different angles depending on the ratio of border to depth you leave (that is, the lip you leave around the box where the frame sticks out to the depth of the box).

      At 1:1, you need to account for a 45 degree angle of visibility (anything larger and the box is not visible). Here is a list of useful measurements

      • border_width:depth_of_box; angle from which the box walls become visible
      • 4:1; visible starting at 14 degrees
      • 3:1; visible starting at 18.5 degrees
      • 2:1; visible starting at 26.5 degrees
      • 1:1 ; visible starting at 45 degrees
      • 1:2; visible starting at 63.5 degrees
      • 1:3; visible starting at 76 degrees
      • 1:4; visible starting at 80.5 degrees
    • If the frame is off center, you match viewing depth and maximize your space usage, but it could look a little wonky from up close.

The diagrams above show an example of how you can know at what point the walls will be visible. If you insert the overhang and depth of the box in "Side a" and "Side b" here: you will get the angle from the wall at which point the box is visible.

Step 2: Materials

Now that you know what size box you need and want, as well as what size frame you will need to cover it to your liking, it's time to gather your goods!

What you needs:

  1. Whatever painting or frame or picture that will go in front of your box.
  2. Wood; if you can use scraps, then go for it, but if you have to buy some, then plywood or dimensional lumber will do the trick. For this you need a piece that is at least as long on it's longest edge as your longest side of your box, and 6 times wider than the depth of your box + 1 inch for loss during cuts (if your box is very rectangular and more than 2x long that it is high, then you can go with a piece that is a bit narrower, do your math).
    • if your frame is huge (several feet by several feet), you may consider thicker wood for the box and using a 1/8 or 1/4 sheet of plywood as a full extra backing to the frame.
  3. 2 drywall anchors and 2 2" screws ; I highly recommend the twist-n-lock type.
  4. Wood glue
  5. Drill and appropriate drill bits for make holes where your 2 mounting screws will go (probably a 1/8th bit)
  6. Appropriate screw drivers
  7. saw (table saw or circular saw will do) with a GOOD BLADE
  8. clamps. I used 8 because I had them, but just 2 will do if you don't mind taking more time.


  • some more screws to fasten the box together, but this is not necessary if you glue it properly. It will look nicer without the screws.
  • if you can't just hang your frame on the box, hinges and some magnets to make it latch (especially if you plan on making it open sideways instead of up/down)
  • pipe clamps if your box is big and won't fit in normal clamps

Step 3: Cutting Your Wood

Start by making long strips that are the width of the depth that you want your box to be.

In the context of this ible, I am using 1/2 plywood . If you are not, adjust accordingly. Also, I am building mine with a 1:2 ratio, for a 2 inch wide overhanging rim and 4 inch depth; yours might look different based on your choices.

You want to cut

  1. 2 side caps ("outside wall") the exact height of your box
  2. 2 "inside walls" 1 inch shorter than the total width you want (because the sides are going to cap the box and their thickness will add 2x 1/2 inches)*. Keep the scraps!
  3. 2 pieces that are 1 inch shorter than your "outside walls". They will be used to add thickness and strength
  4. 1+ piece that is that will be used as the anchor point and to add stregth, others would be shelves
    • This depends on the orientation of your box
      • If your caps are on the side (MOST LIKELY)m then make extra inside walls

      • If your caps are on top, then you want to make more of the item number 3 pieces (1 inch shorter than the caps)
        • I wanted my caps to be at the top and bottom because it's in a stairwell and can't really be seen from the sides at all, but more so from the top and bottom

Step 4: Assembly 1: Outside Walls

All of these assembly steps can be done separately, but I did them at once because I have the tools for it. If you don't don't go spending 100$ on clamps just for this unless you need it (I got mine when doing a mini glider rocker for my kids).

First we need to make the outside wall thicker; this will create a corner in which to glue the inside wall and make the cap easier to handle; it also negates the need to specialty corner clamps. This is a huge cost saving method. I used my scraps for thickness gauge to make sure I had a visual indicator of where the outside wall thickener board went, but I also re-used them once I had applied the glue to properly centre my piece.

Step 5: Assembly 2: Putting in the Inside Walls

So the inside wall will be capped by the outside walls. Now that we have a nice L shaped corner, we have 2 edges on which to rest the inside wall. This means that if you don't have pipe clamps, and your shortest edge fits inside your clamps, you can use either direction for clamping. If you have the clamps that fit (as I do), then by all means clamp in both directions. See the pictures for a visual.

Step 6: Assembly 3: the Back Plate/wall Mount

The back support board was added. It is through this that the screws will go to hold the whole thing up on the wall

Step 7: Hangning It on the Wall

Remove the frame from the box, and hold the box up on the wall where you will want it. Have someone help you if possible, or you can use a level (if you don't have one, your phone should do, but seeing numbers tends to make people obsess about having it exactly at 0 when the phone isn't perfect to start with, and neither is your wall!).

Mark with something sharp through the holes you pre-drilled in the wall plate; put the box down and install the two drywall anchors.

Insert the screws in the pre-drilled holes until they are sticking out about 1/8 inch (2-3mm) so that when you put it up against the wall, the tips will go in the drywall anchor holes to help you hold everything in place as you fasten the screws.

Once the screws are fastened, put your frame back on, and you are done. You can now fill your box.

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