These models are part of the "KontinuumLAB Instrument Kit" project.

I used these keys for my prototype K.L.I.K. MIDI melodica. They function as simple digital switches, by closing a circuit when pressed. The durability of the self-flexing part was tested on a single key, and was still running at 2 million repetitions, although the key was somewhat deformed. The set contains a full octave of "white" keys, and a single "black"
In the photo, these keys have been combined with a box made using the "box ends" from the KontinuumLAB collection.

For full description / explanation, go to the KontinuumLAB YouTube channel: https://www.youtube.com/channel/UCSvGhrAVvAKpWMsooCTBWZQ. This is the video about the K.L.I.K. melodica specifically:

All of the KLIK instruments are meant to be built using the KontinuumLAB Instrument Kit electronics. The use of 3d printed parts is optional, all instruments can be hand-made as well. I will be selling the "K.L.I.K." kit, as well as instruments based on it, in the webshop at: www.kontinuumlab.com

The 3d-printable parts include: mouth pieces, breath sensors, self-flexing melodica keys, wind instrument keys, structural pieces, end pieces for making boxes, membrane instrument "drums", string instrument fret-board sensor bases and even a fully 3d-printed MIDI ocarina.

The KontinuumLAB Instrument Kit is still under development, more detailed descriptions, as well as updates and more designs will be published right here.