With this extension you can assign products to one or more customer groups, so you can hide products for a customer group. after installing the module, a new section will be added to product form in admin panel where you can choose customer groups for product.
You can also add all products to a customer group with one click in module settings page.

Live demo
Back-End: Module Settings
Back-End: Edit A Product
Front-End: Product Page
When you visit above product page, you will see "Product not found" message, because this product is assigned to "Gold" customer group, if you login with the following details as a customer from "Gold" customer group, then you can see above product.
Username and password for customer login:
johnny@doe.com
123456789

Features

• Show or hide products for different customer groups
  
• Add all products to a customer group with one click in module settings page

Install Instructions
- Login to your OpenCart Administration panel
- Go to Extensions > Installer and upload zip file suited for your OpenCart version
- Go to Extensions > Extensions > module > Product To Customer Group > Install and configure it.
- Go to Extensions > Modifications and click Refresh
- Go to Dashboard > Developer Settings (gear icon) > Refresh

Free Installation and Support

• DigitCart Support
• sabeti05 [AT] gmail.com

No core files are changed or replaced.