A couple more history footnotes to help others.
One of the more famous examples of "alternative playfield materials" was EBD as shown in this photo of early production model #1007.
As you can see below, that attempt at innovation failed as not only did the plastic warp, they were still prone to wear due to insert problems of expansion and contraction rates, which is why a "pinball overlay protector" is more effective, if made durable enough to prevent scratching over time with "less than perfect balls". Dents, dimples, and divots (AKA "cratering" as some people here are stating which is not industry used term) however still occur.
The production was stopped almost immediately using these plastic playfields, although repeatedly attempted later again with other titles.
I used to have a full list of games that used these types of playfields (without conducting additional research again) but they were most prevalent during the late 1970s and early 80s at the birth of the SS era. BLY/WMS/GTB would do a few upfront with regular wood playfield games and simultaneously test them at various locations.
There is another key subject and reflective not only of quality of construction, but control as well.
Unfortunately, Stern game testing on location prior to release is something does not do very well and many times today at all (unless you count a few weeks of trade shows), as there is a preference to generate marketing hype for pre order sales (AKA added profit).
In the last couple of years particularly, it has continued to be minimized.
This is another example of loss to the industry and important beneficial requirement to consumers, and not an improvement.
If anything, this observation would be considered a "bash".
Other manufacturers such as JJP are actually still doing this type of testing (while generating interest as in the past) which results in a higher quality product overall. You can do all the engineering testing you want under controlled laboratory conditions, but it does not change the reality of location tests and the REQUEST FEEDBACK provided by potential customers on site.
What a novel concept!
I will leave this posting with quote, that has significant value even today.
"You cannot determine issues, if you do not place games in the environment to which they are operated."
- William T. O'Donnell (Former CEO, Bally Manufacturing Corporation)
If you do not know who he is and what he did, his importance was paramount to the survival and success of not only Bally, but the entire coin operated industry. He was highly respected.