While that sounds like an interesting "bling" project. some parts may not be ideal for plating.
Especially where parts rub together.
Check plating shops in your area. Gold can be plated like other materials (chrome, nickel, etc....)
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
Life Member NRA
Life Member NAHC
Former President of the ECPT (Eifel Combat Pistol Team)