Introduction: Keycap Secret Compartment

About: I'm a maker: I solder, photograph, draw, dye, write, cook, bake, garden.

Hi everyone!

I made a secret compartment in a key cap.

This is very handy if you want to secretly carry a micro SD card.

I 3D-printed the keycap to my key's specifications in 2 identical parts, then taped the SD card to my key, then taped the keycap shut around my key. Voilà. If you need to retrieve the micro card, you can carefully peel back the masking tape or cut it with a sharp blade.


*3D printer (or ready-made key cap)


*Micro SD card

*Masking tape in a color matching the key cap

* Sharp blade.


*Cutting mat

Step 1: 3D Print the Key Cap

Measure the part of the key you want covered by the cap.

Make a shape around the top part of the key:

I used the polygon feature in Tinkercad and adjusted all the dimensions.

Give a thickness of 3 mm to each half, then create a polygonal depression of 1.5 mm so your key and the micro card have room.

I send the Tinkercard file to Cura and then to my printer, a Monoprice Mini Delta.

I used a black filament (draft quality, the nozzle was heated at 200 degrees, speed of 45).

So you'll have 2 halves at the end of this step.

Check that if fits your key nicely.

Step 2: Tape

Tape the micro card to your key.

Then place the two halves of the cap around the top of your key

and use the masking tape to precisely tape all around the key cap

so that your key is secure inside.

Then use the hole in the key cap to slide it on your keychain.

Step 3: End

You can add a sticker to your keycap to decorate it.

And feel secure that should you need to discreetly use a micro SD card,

you can use the one hiding in plain sight on your keychain!

Secret Compartment Challenge

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Secret Compartment Challenge