If you excel at something, it can be hard to describe in words how you differ from someone who is merely competant at it.
A photograph of a finely-made table in your portfolio has a much larger, and much more immediate impact in a job interview than listing the word “carpentry” on your resume.
It can be difficult and sometimes impossible to get photographs from a show you’ve done. Even when you specifically ask someone to take pictures for you, it may take weeks or even months to track them down and get copies of the pictures. The only way to guarantee photographs of your work is to take the pictures yourself; consider the photographs you get from other people to be a bonus surprise.
What goes for production shots goes even more so for process shots. Taking pictures of your prop through it’s various stages of construction are a great way to show an interviewer how you work and how you think. It also gives tangible proof that you know what you’re doing (and eases the mind of those suspicious that you did not do the work yourself). Interviewers love to ask how you achieved something, and having a visual road map of the process in your portfolio can be easier than attempting to describe vague concepts through words alone. Sometimes, you may even teach a new trick or technique to an interviewer, and props people love learning new tricks.
The important thing to remember is that no one will be taking these production photographs for you. You need to make it a habit to take pictures whenever you get to a new stage of your prop’s construction. It will certainly behoove you to learn how to take photographs of your work. It is especially true at the beginning of your career, when you have less of a network and bank of experience to point to your abilities, and the pictures in your portfolio are the sum total of what you have to show for your skills. Sometimes, it can come down to a single interesting and well-documented prop in your portfolio to convince the job interviewer to take a chance on you. That’s certainly happened to me; even when the season has come to a close, the prop master will remember that one prop I had in my portfolio that impressed him.