Elf on himself

Santa needs your help!

All of his elves called in sick today, so you have to return on your only day of vacation this year.
On top of that, it's 'Tag der offenen Tuer' at the north pole,
and many children are already impatiently waiting for their presents.
Build a robot for each child, by combining the required body parts on the working stations.
Keep them happy at all times to score the maximum points!