Mech Shopping cart

Could we get a possible UI for having a shopping cart list for parts to be put on a car?

Ideally, the car would display the parts in the car without charging the customer so that customizing the vehicle can be done easier.

The current system you have to go back between parts to make sure they line up and then liveries and such often only fit certain parts.

The best example would be the S13, there is like 3 different parts that need specific other parts in order to line up and being able to sample all of the parts in a cart system would be ideal for both the mech and the customer.