I did not insert servo motors in this fursuit head. The ears and eyelids are controlled with Bowden cables - no electronic components needed.
Cut the Bowden cables.
Attach one end of the Bowden cable to the lever on the eyelid with polycaprolactone.
Cut the shape of the ears out of a flexible material (I used a old mouse-pad). Use polycaprolactone to stiffen the ear there it should not bend.
Attach the lower part of the ear to the head with polycaprolactone. Test where the ear has to bend down.
Glue a strong band to the head and to the ear. Use a elastic band to hold the ear in the up position.
Attach the Bowden cable to the ear. The ear folds when you pull at the Bowden cable.