Per 
Below is a complete draft for my proposal for an SCP. all criticism is welcome.
Item #: SCP-4XXX
Object class: Euclid
Special Containment Procedures: The apartment building SCP-4XXX occurs in has been sectioned off from the rest of the buildings on ████ Avenue under the disguise of unstable foundations. A 4-meter tall chain-link fence has been erected around the perimeter and has been armed to be able to deliver a 1000 Volt shock. Two armed guards are always to remain in their posts in the foyer at all times unless rotating shifts. All personnel are to step off the property where SCP-4XXX’s anomalous effects occur if they feel the urge to yawn and anyone found yawning on the property is to undergo a physical screening and be detained until further notice. Three extra entrances have been built to provide emergency yawning-exits for guards and any other Foundation personnel and security cameras have been placed around SCP-4XXX for added security. All personnel requesting entry to SCP-4XXX must have approval from no less than 2 Level 2 researchers.
All civilians attempting to enter SCP-4XXX or the property SCP-4XXX is built on are to be immediately removed from the area and undergo a physical screening to determine if SCP-4XXX’s effects have occurred. If all vital organs remain in their original state, subject is to be administered Class A amnestics and released. If SCP-4XXX’s effects have occurred, subject is to be detained and transferred to Site-178 for containment and experimentation. Any necessary misinformation stories are to be created involving the person’s disappearance.
Description: SCP-4XXX is an 8-storey apartment building in ████, Australia. The property the apartment is built on measures 30m x 30m. The apartment itself measures about 15m x 20m and all remaining space on the property not occupied by the apartment is covered in grass and lawn. The view of the apartment and its lawn are invariably described as decrepit and showing signs of great neglect. The flora outside has been shown to be covered in Cirsium Arvense (Creeping Thistle) amongst other weeds and measurements of a single grass blade have been as high as 39.0 cm.
The interior shares a similar appearance to the exterior, showing great signs of disuse and neglect; Furniture tipped over, broken and covered in spider webs are common features of every floor. The top 3 floors have been noted to be completely barren with no walls, furnishings or light sources other than a few windows. However, on each floor, painted on the walls with [DATA EXPUNGED] are the phrases *yawn*, Feeling sleepy yet?, I AM ALIV (sic), It aches, and [DATA EXPUNGED]. The handwriting styles suggest they were mostly made by different people.
When a person yawns on the property designated as SCP-4XXX’s containment area, that person (henceforth referred to as SCP-4XXX-1) experiences a sharp, stabbing pain in one of their vital organs. It is believed that the vital organ replaced is "chosen" at random without a discernible pattern. Inspection reveals the organ will have completely been replaced by a model of it made from copper, iron and several materials including durable plastics, fiberglass and rubber. The replacement organ works on a system of complex gears, pulleys and other clockwork mechanisms and, other than pain and discomfort on it’s appearance, functions like the original organ. After SCP-4XXX-1 has an organ replaced, they will begin to experience the following:
-Sense of confusion and disorientation for periods of up to 12 hours
-throbbing and stabbing pain in replacement organ lasting up to 30 minutes
-skin turning a shiny bronze colour
-a sense of comfort and homeliness inside SCP-4XXX and a desire to stay in SCP-4XXX
After an indeterminate time, these symptoms will begin to diminish and be replaced by the symptoms listed below. The observed time period for this to occur ranges anywhere from 3 hours after initial exposure to 48 hours:
-Shy and hermit like behaviour, a great urge to stay inside SCP-4XXX and violent impulses toward anyone who attempts to intrude on SCP-4XXX-1
-Skin turns a bronze hue at approximately 10x the rate of the previous symptoms.
-Organs begin to be replaced by more mechanical copies. The rate of time that must elapse before a new copy appears shortens after every manifestation (16 hours to 12, 12 to 10 etc.) until there are no more vital organs to replace.
-extreme behaviour alterations (violent disposition, unwillingness to cooperate etc.)
-[DATA EXPUNGED]
-[DATA EXPUNGED]
The result of all above symptoms is SCP-4XXX-2. SCP-4XXX-2 is a bipedal humanoid approximately 30 centimeters taller than the original subject. SCP-4XXX-2’s skin is a sleek bronze and lips, nostrils, eyelids and ears are all absent. Eyes are completely black with no pupil or iris. SCP-4XXX-2 demonstrates great strength, pain tolerance, speed, perceptive abilities and intelligence. SCP-4XXX-2 is also extremely violent both towards regular humans and other instances of SCP-4XXX-2, killing them and mutilating their corpses before consuming them.
SCP-4XXX was brought to foundation attention on █/█/1███ after one instance of SCP-4XXX-2 escaped from SCP-4XXX, killing 16 civilians and injuring 22 others. Local law enforcement handled the instance amid multiple police casualties. The Foundation was called in to investigate the remains of SCP-4XXX-2. In the process they discovered the anomalous properties of SCP-4XXX. The instance of SCP-4XXX-2 was believed to be a homeless squatter that had unlawfully entered the country several weeks earlier. Seventeen other dead instances of SCP-4XXX were found nearby. A necessary disinformation campaign launched.
Indigenous Australians native to the region told stories about a large hollow River Redgum (Eucalyptus camaldulensis) which if one entered, they would only come back out as a “sand-coloured monster with sharp claws and swift feet”. This suggests the potential for SCP-4XXX to have not always existed in the form of an apartment building, but instead having changed appearance to suit common dwellings in the area.
