There are many places where one can buy a 12 volt linear actuator. One can buy a 12 volt linear actuator at popular on the web sources such as eBay, Amazon, and Ali Express.
You have to buy a transformer or converter from 220v to 110v.
A company could buy a linear rail at a number of sites and stores. PBC Linear offers linear rails, guides, bearing, and more. Rollon Corporation also offers linear rails and more. Haydon Kerk offers linear rails, actuators and more also.
Nowhere
Remote Function Actuator Modules can be bought from the car manufacturer. Also, these components are available at specialty car shops.
buy a battery charger
Wait til they come out
Buying a six volt battery is better than 12 volt. If you buy the 6 volt takes up less power so it holds more.
You can buy 6v photocell dusk to dawn switches from Acetek photocells
You would need a 24 volt charger. Connect them in parallel and you can charge them both with a 12 volt charger. Or disconnect them and charge each one separately.
One can purchase a 12 volt light from a variety of stores. Some of the stores that sell 12 volt lights include Amazon, The Solar Store, eBay, and Bulbtown.
u need to buy a new door lock actuator
Yes, but you are limited to the amount of current draw the 120 volt load can apply to the adapter.