A bundle is a group of variants SKUs grouped together under 1 Product Code. This is for OneCart to track the inventory.

1) Create a Product Code to tag all variants and bundles. If you have an existing Product Code you would like to tag your bundles to, skip this step.

Go to:
Goods > Manage Variants > Add Product

2) Create a Bundle 

Go to:
Goods > Manage Variants > Add Bundle

Remember to pick the correct product.

Create a unique SKU for the bundle.

Add the SKUs you would like to have in the bundle.

Click "Save Bundle"

Your bundle is created successfully. :)

If you prefer, here is a short video tutorial for you!