Voice by grandson Tyler

***** The Bottomless Pit *****

(c) by Lawrence Lund

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lookingdown7.jpgClick for full size picture looking down into the pit. completedunitok17.jpgClick for full size picture of the completed unit.
threepiecesbest24.jpgClick for full size picture of the 3 components. You look into the pit, and it appears to have no bottom. As you look deep into the pit you hear the faint voice of a child asking for help. The child has fallen into the pit and cannot get out. While this is a very old illusion, I have never seen detailed construction information on the subject. As I constructed mine, I took pictures and notes and I will attempt to give this information along with pictures of the effect and its construction.
I estimate it took about 20 hours to build this effect and cost less than $100 depending on your glass prices.
Before you attempt to start building it I recommend you read through these instructions and look at all the pictures so you will understand the concept.


This effect is accomplished with 2 mirrored surfaces reflecting each other.
You have probably experienced this in a barbershop or some other place that has mirrors facing each other.
I used 2 pieces of glass, One was a regular mirror and the other a see through or 2-way mirror as you see in the police station shows on TV.
You can see through one side but if you're on the reverse side the glass becomes a mirror. The method of construction allows you to take it apart easily for storage.

Preparing the 2x4's to receive the mirrors:

bpendoff.jpgClick for full size picture. Cut a groove midway along the entire length of the 2x4. This groove will hold the mirrors in place, make the width of the groove 1 1/2 times the thickness of the mirrors. Make the depth of the groove about 3/4 of an inch. A table saw makes quick work of this job. Use a magic marker to mark the top surface of the 2x4 so you will know which side matches which when the board is cut. Now cut 8 pieces of the 2x4 into these dimensions.
4 pieces 23"
4 pieces 25 5/8"

Now to assemble the mirror housing:

bpwithmirror.jpgClick for full size picture. Square 2 23" pieces to the inside edge of one of the 25 5/8" pieces with the groove to the inside and all pieces facing up. Use screws to attach the 25 5/8" pieces. Slide the mirror into the slots with the mirrored side up. Now screw the last end piece to the two 25 5/8" pieces. Make sure everything is square. Repeat the process for the 2-way mirror making sure the mirrored side is facing down. This is important, mark each corner with a number 1-4T for top and 1-4B for bottom. You will be taking the assembly apart for painting and it is best to put it back together the same way it was taken apart. Of course when you do get to painting, make sure you remark them as before.  I also added a 3/8" piece of plywood to the very bottom of the unit for protection of the bottom glass. 4 screws hold it in place.

Now for the walls:

innerwallok29.jpgClick for full size picture of an inner wall. When you pick up your 4x8 3/8 CDX piece of plywood, you might as well get it cut to size. My home Depot makes cuts for 50 cents a cut but usually never charges for it at the register. Even if they do, it is cheap enough. You just have to insure that your dimensions are perfectly correct. I made my walls 3' high and am quite satisfied with that dimension. Then have them cut the 4x8' sheet lengthwise to the width of the inside of one dimension of the 2x4" frame. T hen on the remaining piece cut lengthwise to the other dimension subtracting 2 times the width (3/8) of the wall thickness. That is 2 cuts ($1.00). Now have them cut the 2 long pieces into the height of the walls. If you make your walls 3' high, that is 4 cuts ($2.00). I painted the walls a flat black before attaching the faux stones.

Attaching Brackets:

1x2bracketdetail.jpgClick for full size picture of an attaching bracket.
bracketattachedok25.jpgClick for full size picture of the brackets mounted. To hold the sides together I used short lengths of 1x2 pine. Cut 16 pieces about six inches long. This will make up the 8 brackets for each corner of the top and bottom. Put a dab of waterproof glue on the end of one piece and form an "L" shaped bracket with another piece. Do this for all 8 brackets. After the glue dries, pre-drill and put a couple of screws in for strength. Now lay the assembled mirrored bottom on the floor and place one of the exact fit sides of the wall to the inside of the 2x4 frame. Have someone hold it in place and glue and screw one of the brackets on the wall so that the bracket rests on the top surface of the 2x4. Repeat for the other side. Mark the wall so it can be placed back into the same position on the 2x4 base. Now repeat the procedure for the opposite side wall. Now put both bracketed walls back in the base and slide in one of the remaining side walls. This wall should fit between the other 2 walls. Now put 2 screws (no glue) through the bracket into the side wall. Repeat this procedure for the remaining side. Then do the same for the remaining wall. Repeat this whole procedure for the top, making sure that the bracket is flush with the bottom of the top 2x4.

Installing the light:

opensidecloser31.jpgClick for full size picture of the installed light. On one side wall, measure to the exact center and drill a hole large enough to install the pigtail wires from a light bulb socket.

Aligning the illusion:

Assemble the unit and plug in the light. Look down into the pit and check the alignment of the lights. Hopefully they will appear to go straight down. If they are off, you will have to install shims on the top of the upper brackets to align everything. Use some thin wood stock like a paint stirrer or whatever. Once it is aligned, glue the shims in place.

Making the stone walls:

foamstones.jpgClick for full size picture of the numbered stones. Measure one side wall, the walls should all be almost the same size. Transfer the measurements to the 2x8 sheet of pink foam and with a magic marker draw about 15-20 random stones on the foam. Number each stone starting with the lower left and going to the top. Cut all 4 pieces of foam to the same size. I attached all 4 pieces of foam together and cut out the stones on my band saw. After cutting, I marked front and back of each piece with their numbers. I have a bench sander and I sanded the edge of each piece to simulate a stone. Paint the stones to your liking, I used gray paint with splashes of white and black. I'm sure it can be done better, but it looks good in the final effect. Remember to use latex paint, otherwise solvents may melt the foam. I used liquid nails construction adhesive to attach the stones to the inside walls. If you want, you can repeat the procedure for the outside walls, but if I had to do over again I wouldn't do the outside, too much work.

Adding sound:

I picked up a small radio with a tape deck for $5 at a garage sale. Get a 30-second loop tape from radio shack or some other source. Have a child record a help message on the loop tape. This is just one way to do it. Conceal the recorder at the base of the pit.

Some tips:

People have a tendency to lean on the 2x4 top when they look into the pit. You might want to build a second "leaning" structure around the pit. If any of you have any suggestions e-mail me.

I was thinking of mounting the effect at about a 45-degree angle on the grass and using bales of hay to conceal the bottom of the pit. This way, you can construct a fence to keep people from getting to close to the glass.

Since the top and bottom are easily removed from the side walls, I was thinking of running some temporary 2x2 straps from the top 2x4 to the bottom 2x4 to tie the unit together.  I also did this.

One of my grandsons (Joey) suggested putting a piece of Plexiglas over the top of the unit to keep dirt off it and also protect the top mirror.  This I did and it works fine.

Material list:

2 10' 2x4 (these must be very straight and will be used for the mirror supports)
1 4x8 sheet of 3/8 CDX plywood ( for the walls )
2x2' mirror
2x2' 2-way mirror. If you run into a problem getting the glass, try Alert Glass, 631-666-7000 and ask for Gino.
2 2x8x3/4 foam insulating panels ( to make fake stones, I used the pink kind from Home Depot )
1X2 pine for brackets
Screws, I like wallboard screws.
1 100W light bulb and socket.
2 tubes of Liquid Nails construction adhesive.
Latex paint. Caution!! paint with solvents will melt the foam.

Tools needed to build it:

Router or table saw to cut the grooves for the mirrors.
Drill and bits.
Paint brushes.
Band saw or skill saw.
If any of you tackle this project, please write and let me know how you make out.

I recently added a ladder on the inside. bpladder.jpgClick for full size picture.

The bottomless pit is one of my favorite projects because it's both fun to play with and build. Although, this project does
take a little bit of time to build.
One of my favorite things to do with the bottomless pit is to dangle valuable items above it like watches or tungsten wedding bands and pretend I might drop them in and lose them forever.


Here are comments I have received from people who have built this project:

From "Scott Robinson."
Just finished a version of your pit. The problem that I had was that the cheapest I could find a 2x2 piece of 2-way mirror was about $70. That put the project right out of budget. Here's what I did: I bought a scrap piece of 1/4" 2x2 plexi from Hechingers ($3.00) and bought some mirrored window tint ("Mirror Tint" by Secret Zone) at Pep Boys auto store ($14.00). I applied the tint to the plexi and viola! It works great, and solves the problem of TOTs breaking the glass! You may consider this as a cheap and safe alternative to the 2-way mirror. Thanx again for your wonderful project ideas!
From "Bill Englisbe"
I recently built the pit as described in your plans.  I tend to get carried away with my projects and did so here.  I top coated the stones with Faux granite paint ($7 at Gardenridge) to give it a grainy texture and added dried moss ($3 at Gardenridge) between some of the stones to make it look like mold growth. I cut the groove a little bigger for the bottom and placed a piece of thin plywood below the lower mirror as protection against breakage. I also added a hinged lid to protect the glass and to add to the tale I plan to tell about someone falling in.  Minor details but very realistic.   Can't wait to display it.
From "Ryan Family mst351@pacbell.net"
Great idea. I made mine to resemble a mining shaft.  I used expandable foam to create roots on the inside.  It was the hit of Halloween in my neighborhood.  Thankx for sharing.
From "Michelle"
My pits complete save for a few cosmetic effects. A few of the things I did was:

1) For the inside I used some fabric for an earthy effect.
2) I put a cover over the light with the same fabric on top and some reflective tape on the bottom. This hides the bulb a little bit but mainly its to keep the glare down.
3) I built mine with double walls to hide the cords and a place to hide the tape deck.
4) Some ideas for inside the pit I'm mulling around is to add some vines, make a giant rope cobweb with spiders coming up, fingernail scratches going all the way down, a snakes body on the inside of the pit with the head attached on the other side of the Plexiglas so the effect would be a long snake slithering out, have blood running down the sides or a simple knotted rope.

Michael Marshall
I used your instructions to make a bottomless pit which was introduced at my haunt yesterday.  I got great reviews from the crowd, and innumerable "how did you do that?" comments.  A few changes I made in building:

- I painted all the assembly pieces right after cutting them, which removed the step of have to put the glass holders together twice.

- After cutting the foam stones, I used a knife to randomly cut the edges off the stones instead of sanding them, which I think made the stones look more realistic.  Also, to save time, instead of numbering the stones, I took simply took a piece of foam the stones had been cut out off and put it on top each side, and using it as a stencil went over it with spray paint.  That was a quick way to leave a template on each piece showing exactly were each stone needed to be placed.  Since there were four of each size, it was easy to sort them and find their space on each panel (my young son and daughter helped).

- I used a bunch of "faux finish" techniques to paint the stones (put a basic grey finish on first, then randomly dabbed them with rags and sponges that had been dipped in various flat glazes).  Then used a little bit of fleck stone paint in various colors to finish them off.  The results were very realistic.  In fact, I strongly recommend that anyone who wants to duplicate any form of stone for anything in their haunt put "faux finish" into their web search engine; you'll be amazed at the detailed instructions on some of the sites that come back, and the results can literally be Disney World quality.    Oh - also, the pink foam I got at home Depot didn't melt even when I used spray paint on it.

- Since my home haunt theme is "a haunted cemetery," I made my pit a "bottomless tomb" instead of a "pit a child has fallen into."  I finished the exterior with foam to make it look like a memorial, and built a fake top that appears to have been pushed off the tomb (it lies broken in two pieces by the side).  The whole exterior is painted to look like old marble.  It works well because the "box shape" of your design almost looks like the sort of shape one would find in a cemetery.  

Thanks again for a great design and wonderful instructions!!

Michael Marshall
From: nev_desert_rat

Just a note to let you know another way to create the "stone-wall" effect.
I cut the pink insulation sheet into two parts, 2X3' each, then, using a magic marker, I drew a single line around the 'stones', until the entire half-sheet was marked.
Using an old router cutter, I traced every line cutting a groove a little over an inch deep. (If you'll look at your finished wall and imagine marking between every stone with a marker, it might be clearer) I do suggest using an old router tip, since the heat from the friction bakes the insulation onto the tip.
Then I put a 'roundover' tip in and traced over the groove, rounding the top edge off. (If the original groove is deeper than the 'roundover' tip reaches, no material will stick to the more-expensive roundover tip.) This has several advantages: There's no need to trace and cut out individual 'stones', which means you don't have to replace each stone in exactly the right place; I also spray painted the entire sheet with grey primer and then Faux stone. It's much easier to paint four sheets than to paint almost eighty individual stones! I got a small can of flat black paint from a model-building shop and painted the bottom of the groove then top-coated the entire sheet with clear finish. I glued the sheet to the plywood backing and was done.
Because all four plywood sheets are the same size, it was necessary to trim two inches from two edges of two opposing sheets, along the three-foot side, before gluing them to the plywood. (otherwise, the plywood edges couldn't meet.) I've also put a Plexiglas cover over it, to protect the mirror.

I enjoy your site, and have picked up many good ideas! Thanks!

Da Rat

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Last Modified October 2017