turn everything into OttoDIY head

import OttoDIY-inverted_head_v08.stl and OttoDIY+_head_v08.stl into your Tinkercad.

place the two models on each other.

mark the model OttoDIY-inverted_head_v08.stl as a hole


look in thingiverse for a nice face, download it, and import it into tinkercad.
align the imported face to make the eyes fit for ultrasonic-sensor.

Group all the things.

export your customized otto head.
have fun.