***** The Bottomless Pit *****
(c) by Lawrence Lund
for full size picture looking down into the pit.
for full size picture of the completed unit.
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.
It's not as complicated a job as a Home Advisor builder would do, but it's
important to have a good overview of the instructions. A great deal of
preparation goes into Home Advisor projects. Homeowners can get referrals from
Home Advisor for a
variety of home improvement jobs.
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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, 1 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 1 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
Preparing the 2x4's to receive the mirrors:
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
· 4 pieces 23"
· 4 pieces 25 5/8"
Now to assemble the mirror housing:
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
Now for the walls:
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.
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for full size picture of an attaching bracket.
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:
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:
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
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.
· 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
· 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.
2 10' 2x4 (these must be very straight and will be used for the
1 4x8 sheet of 3/8 CDX plywood ( for the walls )
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.
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.
for full size picture.
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
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.
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.
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
- 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
- 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
Thanks again for a great design and wonderful instructions!!
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
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!