Controllers for electronic are always a challenge. After finding some keys that feel good, it was highly desirable to find a way to modify them to be more sensitive. QTC material was acquired and attempts were made to fit the QTC to the switch hardware.
This is what the switches look like on the inside.
In the first attempt, the QTC material was positioned inline with the plunger.
The reassembled switch is on the left. An unmodified switch is on the right. Unfortunately, it was impossible to solder to the QTC material, so this attempt was a failure.
A second attempt was made to make the switches analog-sensitive: the space between the contacts was filled with the QTC material.
This allows the original switch terminals to be used. Convenient.
But unfortunately, it only sense velocity of the keypress. Continuous pressure or position values are more desireable, so more attempts will have to be made. For example, the QTC could be placed in line with the plunger and a second set of terminals routed to it.