Aeron Arm Index

I have an old-style Aeron chair which uses springs to hold the arms in their indexed positions. Newer chairs, however, use an elastic material which compresses to provide the spring force.

These two parts-- the body and spring-- are similar to the new style index part, but with the narrower tab near the rear like the old index part.

Print the "body" part with PETG since the two tabs deflect in operation.
Print the "spring" part with a flex filament like TPU pr TPE, and make sure it's pretty solid.

There's no clearance between the spring and body: gotta shove that spring part in there.

Update 1: added notch at bottom of "spring" part.

More updates to come: the notchiness is not even in/out, though the part is functional in its current version.