The sequence is something like:
(Iterative) Materials and Methods research and experimentation
The Brief is the most top-down of the steps; this is where you take a hard look at the whole project and parameterize it; define how much you are willing to invest in time and money, whether it will involve new methods and materials, etc.
For this prop, the Brief is as follows:
Make a Chinese Hand Gong for use in upcoming production
* Must be light enough for young actor to hold comfortably, but tough enough to withstand the rigors of stage use.
* Does not need to make sound.
* Should be realistic, not toy-like or obviously prop-like.
* And yet, should be oversized and bold enough in design to read from stage distance.
There's another pair of goals that belong in the brief as well, even though they are super-goals of the entire project:
* Should be fun and look good so I can have another prop build to my name.
* Should be good-looking enough -- and practical enough -- to sway the director into finding a way to use it.
The latter is because this gong is a key part of the direction I want to take the sound design, and if I don't do something like put a gong into their hands, they may not give me the physical action on stage I want to pin my sound effects into stage reality.
In any case, always include the super-goals when you brief a project. You need to understand why you are doing it and how it fits into your life and work before you can properly plan the assets to accomplish it.
Research: the intent here is to refer to the gongs of the Peking Opera orchestras. Which have specific types and names but at least one resembles marginally a common hand or hanging gong that is widely exported as an "ethnic artifact." According to research, it is just acceptable enough to pretend that a hand gong with the particular shape and pattern shown above is actually part of an operatic percussion ensemble.
Of course, in the operatic mode that particular gong is small -- for the styles I'll be representing most often in the sound picture, 8". They sell them up to 30", and 20" is seen in the pit -- but as accompaniment for quieter scenes, usually.
(One basic distinction that can be made is between "domestic" and "military" percussion, with the latter being used for all scenes of fighting and armies and so forth, and the other for basically everything else.)
(But we are talking about a variety of forms that evolved over 500 years of performance in many more disparate communities than there are nations in Europe with their own operatic traditions. And if you recognize the difference between Puccini, Mozart, and Wagner, you can definitely see that any blanket statement about "Chinese Opera" is bound to be incomplete!)
As per the draft stages above, research would usually end with a Plan. Often, a scale drawing. You will always research; even something created from scratch may be referring to artistic trends or functional forms. And much of what you learn is hard to commit to paper...but it helps tremendously if you can collate into one place (aka a drawing) all the key lines and dimensions of the thing.
In this case I'm not worried about it. The way in which the truncated-cone shape interacts with the painted ring is clear enough to be self-documenting. Instead this falls closer to being a formula; if I have one fixed dimension, I can derive the others from it.
I like to have two different minds during a project. I start with describing what the thing should be (if I had infinite time and resources), before I move on to what the thing will be (aka, what is practical to build.) I think it is a mistake to short-circuit the process by going immediately to how you can fake up some approximation, because it closes you off from discovering ways to make a better prop. Or whatever it is you are designing.
(I did this to myself as a lighting designer too; I would draw up a plot as if I wasn't the poor soul who would have to hang it).
The Materials and Methods is where you move across this divide. I describe it as iterative because you will have an idea, hit the stores or bend some metal or something, realize you can't find that material or that it doesn't look right, and move on to an alternate -- quite possibly, an alternate you stumbled upon while you were looking for the first thing.
For cheap props with flexible dimensions, the first stop is usually to see if there is anything already in the world that will fit the bill. You have to be exquisitely sensitive to real shapes, and not be mislead by simplified approximations of them. Far too often, real-world objects will have inconvenient details that are too labor-intensive to be worth attempting to alter or remove.
As a specific, I discovered some bamboo disposable plates that are close to the right shape for the face. They lack the thickness, however. So they would work pretty well if I wanted a lot of semi-acceptable gongs cheap. But the labor in adding a thick edge with the right curve may be enough that it is worth hand-carving the entire shape -- especially as the latter gets a more accurate profile overall.
I also looked at frisbees, which have the incorrect curve on the edge, and inevitably surface ridges that would be difficult to remove or hide. I could do a more generic sort of gong from one, but it doesn't have the specific shape of the Peking Gong.
The twin constraints of weight and strength are leading me away from MDF/bondo, and the constraint of cost leads me away from casting as an option. At the moment my best consideration is carved expanded foam that after being sealed will be coated in resin for strength.
Which leads into the final stage; where I start actually carving into some material and see if I am getting the shapes and the surface quality I want with an acceptable amount of labor.