Originally Posted at Creepypasta.com
Though written about in fiction occasionally, the mirror box is quite an old invention. Being inside of one can be enlightening or traumatizing for the witness who bears its burden. The procedure is simple, though finding and preparing the materials required might take some time.
The materials to construct the box are:
-Six square metal sheets, slightly taller than the witness. The length should never exceed the height of a witness with raised hands. One of them should be larger than the rest by at least the thickness of the sheets themselves. The material should preferably be made of graphite or lead alloy for the most prominent effect.
-Five nearly perfect, aligned mirrors, sealed upon the metal plates. Each of the 5 will form the sides and bottom of the inner box. One larger mirror should be attached to the large metal plate, which will be used for the top.
-A simple light source of pure white or bright yellow. The light source should emit in almost all directions. Candles can be used, but carbon dioxide and monoxide poisoning is a problem. The light source should not be planted upon the mirrors or receive any outside energy. Construction techniques are left up to the witness.
-Two or three alarm clocks. An extra alarm clock of any kind is also needed. Watches are alright, but not suggested due to the small type face and hands.
-Wear simple clothing.
-Do not bring any other objects. Witnesses have often crowded the box, causing it to become either useless or highly dangerous. This includes jewelery, food, weapons, or religious materials such as beads and crucifixes.
-An assistant is required to help the witness in and out of the box and get help in case of emergencies. The assistant should be trusting and as strong willed as the witness.
-Several Blankets, water, medical remedies, and a first aid kit.
When the box is complete and ready to use, prepare the alarm clocks to ring around ten minutes after the witness’ planned entrance. Depending on the material used for the box itself, the time of day will not matter, but a night during a new moon is suggested. Despite intuition, sound does not play a large role in the event. The witness should use a small unattached ladder to enter the box. The top should already be placed upon the box, with an opening large enough for the witness to enter. Once inside, the witness should be handed the light source and the clocks (one should be kept with the assistant). The outside assistant should ask sincerely whether the witness is alright. Once confirmation is given, the top should be moved to seal the box. The witness may turn on the light source once the box is sealed. At any point should the witness ask to leave the box (if soundproof, tapping should be used), ONLY the top should be opened. The witness may do it themselves, since the top of the box should be easily reachable. Once ten minutes are up, ALWAYS remove the top, regardless of what the witness says. Some witnesses may plead to stay inside the box, even suggesting great danger should it be opened. The assistant should never trust those pleas. Suffocation is only one of many concerns should the witness stay too long in the box. Once the top has been slid opened, place the second ladder in the box to allow the witness to leave. If the witness has any serious wounds, or discoloration, call for medical help.
Should you happen to meet a witness, never trust what they say about their experience, and never ask them for the time or where the antumbra meets.