What are ways to modify a key for tactile differentiation?

Question

One has many keys on a keyring. The keys are more-or-less identical.

Example:

How can one modify a key to make it stand out from the others when rifling through them with one's fingers? It is dark and any visual distinctions cannot be perceived.

Related:

Lifehacks SE: What is a good way to organise and identify keys on a keyring?

Most of the answers contain visual distinctions (nail polish, permanent markers, colored key caps, stickers, spray paint, etc.). Drilling holes and filing notches into the keys were recommended, but this is a hassle and requires special tools.

Answer 1

The geometrical approach:

For someone who does not want to modify the key itself, use a deliberate disorder:

If all keys are on one ring, have all keys oriented in the same direction, the one to be found in the dark in the opposing direction.

For multiple rings like in your question, put the special key on it's own ring. If more keys are alone on a ring, use a short "chain" of two rings so that the one is singeled out or slip a tiny object like a bead onto the key ring. This should not add much bulk to the key ring like a special pendant might.

Answer 2

Use woolen threads of different colors to differentiate the keys. That will not only help you differentiate your keys but also looks colorful and elegent.

Answer 3

You could dip the head of the key in a rubber coating product (google "dip rubber coating" for example products). This would give you a visual and a tactile way to distinguish the key. These products are also commonly used to put a nice non-slip grip on tool handles.

A cheaper alternative would be to dip it in rubber cement, but I'm not sure how well it would hold up over time.

Answer 4

The visual approach that also works in the dark:

For one single key, a plastic cap or ring (costs a few cents at a hardware store) is probably the easiest solution.

My choice though would be nailpolish - there are some that have a sandy or grainy or rubbery texture and I have some already at hand. So the one that doesn't slip when grabbed is the key in question. Ask a girlfriend if she can spare a few drops, if necessary.