Hi,
I usually make a personalized discount that he can use to buy another thing and delete the amount of the returned product
You can issue a gift card instead of coupon code. The only thing is that it could only be a fixed amount and there is no conditions you can apply for it but probably for your case that’s quite enough.
- I want to customize gift card on the store, personalize the graphics and give the possibility to the client to choose if he wants to receive it digitally to email or physically (printed at home)
You may try to search in App Store Gift Card Hero app. It has ready-made designs, also allows to upload your own, schedule send to a recipient or send it to yourself and print at home. Also, it modifies boring Shopify gift card page and makes it animated.