Ball

Stop hurting yourself and print this ball to hold the wire :) Would work for any ~1,5 mm wire. If you manage to get 1,7-1,75 mm that would be even better.

Cut approx. 160 mm for MMU2S and Mk3, or 130 mm for Mk3S/+ (different filament path length)
Bend the end of the wire to secure it inside the cavity and superglue it.