1. Measure your cable ends
2.
Pick up a package of new cable ends (good to have spares)
3.
Buy an Odyssey Slic cable
4. Mark your desired inner wire length
5. Cut the inner wire about 1" past your mark from step #4
6. Slide a new cable end onto the inner wire, making sure the larger hole faces towards the end of the cable
7. Lightly clamp with pliers/vice/etc the inner wire at the mark you made in step #4. The new cable end should be resting here now
8. Fray the 1" of extra inner wire that is sticking past the new cable end out (this makes it impossible to pull back through after completing the process)
9. Grab your soldering iron and heat up the cable end/wire
10. Let the solder fill up the little pocket in the cable end, around the now-frayed inner wire
11. Be careful not to let the solder fill the cable down past the cable end. This will make it brittle
12. Cut off excess frayed wire and file down the solder until it is smooth and round again.
13. Chug a beer because you just made a custom cable for about $10 instead of paying $50 for one.
Also, I highly suggest
pliers similar to these when cutting braided cables and their housing: