For flex sensing I ripped and milled birch to 1mm thickness and created laminations - both with clamps and a vacuum bag. The first attempt failed but the second works well.

Laser etched and cut inlay of sensor

Homemade plywood

Layers

Glue up

Broken first try

Broken first try

Try 2: birch and cork in a vacuum bag

Try 2: birch and cork in a vacuum bag

In hand pump vacuum bag

Birch + Cork + Flex sensor

Working