How to create a bundle from different variants of one product?

Imagine you have a pen on your site which has 8 colors as pen variants and you want to sell a full set of this pen (8 pens with 8 different colors) as a bundle. The point is you should add each one of these variants to the bundle as distinct products.
Here are the steps to follow to make it happen by Fast Bundle app.

1- Go to the Fast Bundle admin panel -> click on the "Create new bundles" button -> Select Bundle.
2- Click on the Browse button to select the products. Select the pen product. Then make sure to only select the first variant of the pen product and deselect all other variants. Click on the "Done" button.
Then your page looks like the below screenshot. Once again, click on the Browse button.
Find the pen product. This time select the second variant and deselect other variants.
Repeat the process until all variants are selected. Then the bundle edit page will look like the below screenshot.
And the bundle will look like this:
So your customers can buy the full set of pens (8 pens with 8 different colors) as one bundle.

Example and screenshots courtesy of glonde.myshopify.com.