In Japan, when a pet passes away, it is usually cremated and its cremated remains are buried in a pet cemetery. Memorial services for pet is also hold.
In relation to death of a pet, many kinds of pet coffins are sold. Among them, assembly type coffins made of cardboard seems to be the most popular. (See the below image)
The cardboard is a cheap, light and strong material, so that it is well suited to pet coffins.
Some designs of pet coffins have been registered with Japan Patent Office.
The following image is a design of a pet coffin that was registered in the past.
On the upper surface of the coffin, a window for viewing the body and two holes for flower arrangement are formed.
The owner of the above design rights was a historical packaging materials company. It's interesting this kind of company entered into pets industry.