You can't max all crafts on a level 10 alt, you need more skill points than that character can get. So your choices are:
- many low level crafting alts,
- one high level (lvl50) crafting alt with almost no combat skills worth mentioning. You can even level this alt normally and then reset all skillpoints and invest them in crafts.
- crafting on your main.
- any combination of the above. For example, 4 crafts on the main character and 2 on a middle-level alt.
I chose the third option with my main crafting everything. There are enough skill points to do that if you are careful in collecting all skyshards and doing the main quests in your native alliance and in veteran areas.
You can't craft the best set pieces on your alt unless he has finished the Mage Guild quest line, the Fighter's Guild quest line, and the main story. If there was ever a good reason to craft on your main, that would be it.