Deadly Friend
Paul is smart and nerdy and makes his own retarded robot friend BB, retarded because all it can say is it's own name "BB! BB!" and make stupid baby sounds which are supposed to be endearing but because it's voiced by a raspy old man just make him sound like a pervert.
He meets drippy Tom and abused Samantha and it's all fun and games until BB gets shot and Samantha gets killed by her father.
Luckily as well as studying robotics 15 year old Paul is also a whiz at brain surgery and ends up making a Samanatha/BB zombie which doesn't know if it's a girl or a robot and promptly goes on a murdering rampage.
There's 3 gore scenes which seem inserted ad hoc to make this a horror film but it's more sci fi and there's no sex or cussing so seems surprising charming.
Oh and this is directed by Wes Craven.
YES - the track playing over the credits has to be heard to be believed.