Use a connection that is mechanically secure, electrically solid, and re-tensionable. A common approach: a small insulated post or pivot arm on each carriage, the wire wrapped and clamped under a screw terminal or a brass crimp lug, with the heating current fed to that terminal. One end is fixed; the other pulls through a spring for tension.
Keep the clamp away from sharp bends (kinks become breakage points), isolate it from the frame so current only flows through the wire, and make it quick to re-thread — you will replace wire occasionally. Avoid soldering nichrome directly (it does not solder well); mechanical clamping is more reliable.
Keep the clamp away from sharp bends (kinks become breakage points), isolate it from the frame so current only flows through the wire, and make it quick to re-thread — you will replace wire occasionally. Avoid soldering nichrome directly (it does not solder well); mechanical clamping is more reliable.