I usually use a rotary tool accessory set with different cutting bits and or discs,
you need to take a mold or shape matching gauge to replace what you remove
back to the original shape again ,or make a custom foam handle to your specs.Most Volkls have a solid lead weight hot glued between the hairpin to
counter weight the frames , I like the silicon between the hairpins and inside
the tubes ,a little tungsten power if needed !!