A cat door for people: a “people door,” if you will.

Background:

A cat owner may install a “cat door”—a cat-sized flap—in a door in their house (Fig 1). This allows a cat to travel freely even when the human-sized door is closed.

Fig. 1: Even if the main door is locked, the cat can travel through the cat door. Convenient!

A cat door also removes the need for the cat to carry a set of keys.

Proposal:

But why should cats get all the convenience? It’s time for humans to also get the same hands-free keyless entry door options as cats! Behold, the “Cat Door For People” (Figure 2).

Fig. 2: This “person door” is a metal grille that is shaped to the exact dimensions of a specific person, which could, perhaps, securely filter for only a very specific person. See both the “front facing silhouette” type of grille (left), which are entered straight-on, and the “sideways silhouette” grilles (right), which are entered by turning sideways and shuffling through.

It’s likely that one grille would not be sufficient to restrict entry to a specific person. Perhaps a series of closely-spaced metal grilles at different angles would be required. However, the convenience will definitely make this worthwhile.

One possible pitfall of this system is that any small animals (e.g. rats, snakes, scorpions) will be able to easily pass through a sequence of human-sized cutouts. Additionally, heating and cooling a house will become nearly impossible if there is an grating that is open to the outdoors at all times.

Fortunately, there is a simple fix to this issue: simply add some sort of solid horizontally-pivoting wooden plank to one side of the grille. It could even have a lock and handle, for additional security.