Costs I dont remember exact costs Its been a couple years since Ive had one made. But I think about $10-15 ea

stamping on metal. cheap enamel paint. Spray it out on a piece of glass ( or something similar ) roll the stamp in the paint and stamp the part you want .

FYI, practice a few times to get the hang of it

I've had quite a few made. from heater box, axle stamps, and radiator hoses

On hoses I use silk screeners ink. Seems to work the best