If you dissatisfied with the attitudes or the weights of morse keys then this key is exactly the correct key for you.
It lies always ideally between the fingers and is extremely light.
No, I am not the developer of this thing. This honour is entitled to Gerd Lienemann, DF9IV. He came on this idea and published it in the QRP-Report .
The principle is simple. A contact of the CWF finger morse key is pushed on the thumbs and a second one onto the index finger. To these contacts the two-wire line is attached to the transceiver. By touch together of the two contacts you can now form the CW signs according to your desires.
As materials you can use everything, which fits on your fingers. Here briefly a few possible variants: metal foils from the hobby store, which are bent together and soldered to suitable rings, ribbons with additional rivets as contact areas or thimbles from mothers sewingbasket.
I used the pulling fingers from the music shop, also suggested by Gerd. There are in different sizes. In addition you can squeeze together or apart-bend it somewhat, so that they fit always firmly on the fingers.
Still an important note at the end. If you use more efficient transmitters (particularly tube transmitters), then absolutely pay attention to an isolation of the contacts. Otherwise the first CW sign with this key is your latest one.
 Gerd Lienemann, DF9IV: CWF − Die Fingermorsetaste. QRP-Report 3/2002, p. 13