Per popular request, here is a tutorial on how to make any pen a flex pen by extending the tines slit. Hope you find it useful.
Cutting discs:
https://www.dedeco.com/ultra-005-discs-7-8x-005-25-bx/?gad_source=1&gclid=CjwKCAiAk8G9BhA0EiwAOQxmfjoFPGvB48ow9jaR4lGzJu_wgi2CZlid5FqWat__S3eR-d5-JLGcrxoCZIIQAvD_BwE
Clamp:
Manfrotto from Amazon
Magic arm: footage magic arm from Amazon
Dremel
Magnifying glasses from Amazon.