I have order 4 12V DC
valve from ebay, free shipping wow, 2 week later noticed it take 20-30 business day for delivery
So I made one today.
Got 2 of this from one of the local appliance repair shop.
and one of this was laying around
I don't have a complete step by step illustration but here is how it looks like on the end.
I don't like the idea to have 110V not insulated solenoid exposed.
Simply I gridded of the existing 110v coil with a dremel tool, than using a cordless drill winded up the wires from the coil of the old doorbell.
Solenoid was free, doorbell was free, all I spent is $3 for the fitting.