“We like something more when we’ve invested more effort into it”
More effort leads to more love (but only when we are able to complete our actions). Customization is about more than individual preferences. It is also about the effort put into it. This customization effort increases liking.

This effect is also called the ‘Ikea-effect’, since Ikea lets it’s customers assemble their own products.

The IKEA Effect from Advanced Hindsight on Vimeo.
Scientific research example:
Imagine you’re given a sheet with clear instructions on how to create an origami crane. Then you make one. Dan Ariely found that you value your own creation more