Craft Essences full... what to do?

If the CE are 1 star use them as fodder to level up your better CE. If you don't have Imaginary Element or Kalescope limit break Dragon (probably mispell it name) to use as substitute.

probably too late for this, but you should be turning your 1-2 star CEs into craft bombs. Its a lot to explain and I wouldn't do a very good job of it, so here is a quick tutorial on it. If you do it properly, you'll save yourself tons of grief: https://www.youtube.com/watch?v=8kte4gHCiAg

You can put 3-5 star CE's that you don't usually use in the second archive to save space, same can be done with servants.

Turn the 1-2 star CE's into CE bombs to level up other CE's that you use often, unless you don't have their higher star counterparts yet.

Turn 1-2* CE to CE bomb and sell all 3* CE you don't need for Mana Prism.Don't feed the 3* CE and above on other craft cause it would be such a.waste.