Test subject but the subject is an inanimate object

I'm looking for a synonym(?) for ‘test subject’ that is applicable when the subject is an inanimate object.

I've tried using the thesaurus looking for synonyms of 'test subject' but it's only offering me alternatives that describe a living subject such as 'guinea pig'.

The phrase it's being used in would be:

Here is an overview of the test subjects being used for this experiment

I've considered the following words:

• examinee
• testee
• subject

But these all feel like they are referring to a person or an animal instead of to an inanimate object. I'd prefer the word to be formal as it's being used in a research context. The 'best' word would be a single word that implicitly conveys the fact that the subject of the sentence is in fact, an inanimate object.

Note: The reason that ‘subject’ is not applicable lies in its definition:

subject - 6. a person who is subjected to experimental or other observational procedures; someone who is an object of investigation; "the subjects for this investigation were selected randomly"; "the cases that we studied were drawn from two different communities"

In trying to say they're test things but not things-for-test but specifically the things-under-test...

article - a particular item or object.

But that's still not entirely perfect. So, acknowledging that if you say "test device" it's not totally clear whether it's for test or being tested, my industry also uses DUT as an acronym for device under test.

DUT - a manufactured product undergoing testing

I'd probably use article or device in your case. Object is another possibility.

For an experiment, the word you want is probably sample:

a specimen taken for scientific testing or analysis.

It’s both widely understood and used in formal writing. Here’s an example from a research paper:

The characteristics of initial samples of paper are given in Table 1.