How can i create a custom map with zip code boundaries for specific zip codes. I have a list in CSV

Here's a way to create an Google Maps-based custom ZIP Code map on the fly by passing a comma-separated list of ZIP Codes as a URL parameter.

You can also choose whether or not you want to show the merged ZIP Code merged boundary (e.g. to represent a service territory, sales territory or delivery area)

And optionally create a title for the map (use the + character to represent spaces in the title). Here's an example URL:

There's a write-up on this here:  Create a custom County Lines map or ZIP Code-based Sales/Service/Delivery Territory map on the fly -- overlaid on Google Maps