Fish's Undead Rising is another mod offering new mobs to the game and it also has an Ectoplasm drop (mod_lavacow:ectoplasm). The recipes can be manually tweaked but specifically the LilVessel is fussy for which type of Ectoplasm it gets, so full compatibility would be appreciated!

I believe just adding ore dictionary support for the LilVessel (and possibly for the recipes) would suffice, then other types of Ectoplasm could be added on the go.

Added with latest alpha release. Thanks Jon