here's a thought, how about letting us craft an epic augment slot onto an existing epic item. there are many epic items in the game with no slots that could really benefit with being able to add a slot. limitations would need to be put into place such as:
no item could have more than two slots
no item could have more than one of each color slot
armors could only have a blue or colorless added
martial weapons could only a red or colorless added
caster weapons could only have blue, violet, or colorless added
wearable items could only have a yellow, green or colorless slot added
cost of adding a colorless slot should be lower than adding any of the slots that have a color due to the lower versatility of the slot.
make the cost be a fairly large number of epic tokens and/or epic raid tokens and also be able to be purchased with turbine points.